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Questions tagged [oeis]

The On-Line Encyclopedia of Integer Sequences (OEIS) is an online database of integer sequences.

The On-Line Encyclopedia of Integer Sequences (OEIS), also cited simply as "Sloane's", is an online database of integer sequences, e.g. A000045 [0, 1, 1, 2, 3, 5, 8, 13].

OEIS records information on integer sequences of interest to both professional mathematicians and amateurs and is widely cited. As of 22 August 2015 it contains over 260,000 sequences, making it the largest database of its kind.

Each entry contains the leading terms of the sequence, keywords, mathematical motivations, literature links, and more, including the option to generate a graph or play a musical representation of the sequence. The database is searchable by keyword and by subsequence.

Source: Wikipedia

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Fastest way to filter the A010784 sequence

The A010784 sequence at OEIS is the sequence containing only numbers with distinct digits. This is a finite amount. What I've been trying to do is find several numbers in this sequence with certain attributes. E.g: 6 is a distinct number of…
Aeveus
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Code to form a nxn matrix with oeis sequence A072567

i need to code in c++ to form a nxn matrix where 100 <= n <= 1000 with oeis A072567 sequence. This mean wherever i place '1' it should not form a rectangle. the rest places can be filled with 0 here is 21x21 matrix with 105…
batis
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Is there a more Pythonic way of coding this recurrance relation re: OEIS A077947

I am working on a thesis regarding Jacobsthal sequences (A001045) and how they can be considered as being composed of some number of distinct sub-sequences. I have made a comment on A077947 indicating this and have included a python program.…
J W Jeff Helkenberg
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Convert PARI program to C++

I found a sequence of interest in OEIS and I want to generate the same sequence in C++ for a programming competition solution I am working on. However I hit a roadblock understanding how the program given in the sequence page works. Here is the…
Sri Hari Vignesh
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can a neural network be trained to recognize abstract pattern forms?

i'm curious as to the kind of limitations even an expertly designed network might have. this one in particular is what i could use some insight on: given: a set of random integers of non-trivial size (say at least 500) an expertly created/trained…
snerd
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Programmatically finding solutions to OEIS A001839

Okay, so here is an integer sequence. Over at the math stackexchange, I learned what this sequence means. Basically: Given n item, a(n) is the number of groups of three you can create where no two groups have more than one item in common. So if…
fnsjdnfksjdb
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Verifying output to "Find the numbers between 1 and 1000 whose prime factors' sum is itself a prime" from Allain's Jumping into C++ (ch7 #3)

The question: Design a program that finds all numbers from 1 to 1000 whose prime factors, when added together, sum up to a prime number (for example, 12 has prime factors of 2, 2, and 3, which sum to 7, which is prime). Implement the code for that…
ironicaldiction
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Generate and Enter Value for OEIS Sequence in Python?

This is a rather difficult challenge for me as I am new to Python. How would I write a program in python based off this sequence function: http://oeis.org/A063655 and does the following: It asks for the value of the sequence and returns the…
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