cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A305822 Number of irreducible factors (counted with multiplicity) of the (0,1)-polynomial encoded in the binary expansion of n has when it is factored over Q.

Original entry on oeis.org

0, 1, 1, 2, 1, 2, 1, 3, 2, 2, 1, 3, 1, 2, 2, 4, 1, 3, 1, 3, 2, 2, 1, 4, 1, 2, 3, 3, 1, 3, 1, 5, 2, 2, 2, 4, 1, 2, 2, 4, 1, 3, 1, 3, 3, 2, 1, 5, 2, 2, 2, 3, 1, 4, 1, 4, 2, 2, 1, 4, 1, 2, 3, 6, 2, 3, 1, 3, 1, 3, 1, 5, 1, 2, 3, 3, 1, 3, 1, 5, 1, 2, 1, 4, 2, 2, 1, 4, 1, 4, 1, 3, 2, 2, 2, 6, 1, 3, 3, 3, 1, 3, 1, 4, 3
Offset: 1

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Author

Antti Karttunen, Jun 10 2018

Keywords

Crossrefs

Cf. A206074 (gives the positions of 1's), A206719, A257000, A304751.
Cf. also A001222, A091222.
Differs from A277013 for the first time at n=65, where a(65) = 2, while A277013(65) = 1.

Programs

  • PARI
    A305822(n) = vecsum(factor(Pol(binary(n)))[, 2]);

Formula

For all n >= 1, a(n) >= A206719(n).