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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A351450 a(n) = A064989(A048250(A003961(n))).

Original entry on oeis.org

1, 1, 2, 1, 1, 2, 2, 1, 2, 1, 5, 2, 4, 2, 2, 1, 3, 2, 2, 1, 4, 5, 6, 2, 1, 4, 2, 2, 1, 2, 17, 1, 10, 3, 2, 2, 10, 2, 8, 1, 7, 4, 2, 5, 2, 6, 8, 2, 2, 1, 6, 4, 6, 2, 5, 2, 4, 1, 29, 2, 13, 17, 4, 1, 4, 10, 4, 3, 12, 2, 31, 2, 3, 10, 2, 2, 10, 8, 10, 1, 2, 7, 12, 4, 3, 2, 2, 5, 25, 2, 8, 6, 34, 8, 2
Offset: 1

Views

Author

Antti Karttunen, Feb 11 2022

Keywords

Crossrefs

Programs

  • PARI
    A003961(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
    A048250(n) = factorback(apply(p -> p+1,factor(n)[,1]));
    A064989(n) = { my(f = factor(n>>valuation(n,2))); for(i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f); };
    A351450(n) = A064989(A048250(A003961(n)));

Formula

Multiplicative with a(p^e) = A064989(q+1), where q = nextPrime(p) = A151800(p).
a(n) = A064989(A048250(A003961(n))).

A351455 a(n) = A064989(A001615(A003961(n))).

Original entry on oeis.org

1, 1, 2, 2, 1, 2, 2, 4, 6, 1, 5, 4, 4, 2, 2, 8, 3, 6, 2, 2, 4, 5, 6, 8, 5, 4, 18, 4, 1, 2, 17, 16, 10, 3, 2, 12, 10, 2, 8, 4, 7, 4, 2, 10, 6, 6, 8, 16, 14, 5, 6, 8, 6, 18, 5, 8, 4, 1, 29, 4, 13, 17, 12, 32, 4, 10, 4, 6, 12, 2, 31, 24, 3, 10, 10, 4, 10, 8, 10, 8, 54, 7, 12, 8, 3, 2, 2, 20, 25, 6, 8
Offset: 1

Views

Author

Antti Karttunen, Feb 12 2022

Keywords

Crossrefs

Coincides with A326042 on squarefree numbers (A005117, and apparently on no other numbers).
Cf. also A351441.

Programs

  • PARI
    A001615(n) = if(1==n,n, my(f=factor(n)); prod(i=1, #f~, f[i, 1]^f[i, 2] + f[i, 1]^(f[i, 2]-1))); \\ After code in A001615
    A003961(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
    A064989(n) = { my(f = factor(n>>valuation(n,2))); for(i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f); };
    A351455(n) = A064989(A001615(A003961(n)));

Formula

Multiplicative with a(p^e) = A064989((q+1)*q^(e-1)), where q = nextPrime(p) = A151800(p).
a(n) = A003557(n) * A351450(n).
Showing 1-2 of 2 results.