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.

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A380528 Smallest prime p such that p^p is a divisor of A380459(n), or 1 if no such factor exists, where A380459(n) = Product_{d|n} A276086(n/d)^A349394(d).

Original entry on oeis.org

1, 1, 1, 2, 1, 1, 1, 2, 2, 3, 1, 2, 1, 1, 2, 2, 1, 3, 1, 2, 2, 3, 1, 2, 2, 1, 2, 2, 1, 3, 1, 2, 2, 3, 2, 2, 1, 1, 2, 2, 1, 5, 1, 2, 2, 3, 1, 2, 2, 3, 2, 2, 1, 3, 2, 2, 2, 3, 1, 2, 1, 1, 2, 2, 2, 3, 1, 2, 2, 3, 1, 2, 1, 1, 2, 2, 2, 5, 1, 2, 2, 3, 1, 2, 2, 1, 2, 2, 1, 3, 2, 2, 2, 3, 2, 2, 1, 3, 2, 2, 1, 3, 1, 2, 2
Offset: 1

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Author

Antti Karttunen, Feb 09 2025

Keywords

Crossrefs

Cf. A129252, A276086, A349394, A380459, A380468 (positions of 1's), A380529 [= a(A005117(n))], A380530 (positions of records).

Programs

  • PARI
    A129252(n) = { my(pp); forprime(p=2, , pp = p^p; if(!(n%pp), return(p)); if(pp > n, return(1))); };
    A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
    A349394(n) = { my(p=0, e); if((e=isprimepower(n, &p)), p^(e-1), 0); };
    A380459(n) = { my(m=1); fordiv(n, d, m *= A276086(d)^A349394(n/d)); (m); };
    A380528(n) = A129252(A380459(n));

Formula

a(n) = A129252(A380459(n)).
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