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.

Showing 1-2 of 2 results.

A339895 a(n) = A339894(n) - A061395(n).

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 2, 1, 0, 1, 0, 2, 1, 0, 1, 2, 0, 0, 1, 1, 0, 1, 0, 1, 2, 0, 0, 2, 2, 2, 1, 1, 0, 3, 1, 1, 1, 0, 0, 2, 0, 0, 2, 2, 1, 1, 0, 1, 1, 2, 0, 3, 0, 0, 3, 1, 2, 1, 0, 2, 3, 0, 0, 2, 1, 0, 1, 1, 0, 3, 2, 1, 1, 0, 1, 2, 0, 3, 2, 2, 0, 1, 0, 1, 3
Offset: 1

Views

Author

Antti Karttunen, Dec 21 2020

Keywords

Crossrefs

Cf. A339897 (first occurrence of each n).

Programs

  • PARI
    A000523(n) = if( n<1, 0, #binary(n) - 1); \\ From A000523
    A122111(n) = if(1==n,n,my(f=factor(n), es=Vecrev(f[,2]),is=concat(apply(primepi,Vecrev(f[,1])),[0]),pri=0,m=1); for(i=1, #es, pri += es[i]; m *= prime(pri)^(is[i]-is[1+i])); (m));
    A339894(n) = A000523(A122111(n));
    A061395(n) = if(1==n, 0, primepi(vecmax(factor(n)[, 1])));
    A339895(n) = (A339894(n)-A061395(n));

Formula

a(n) = A339894(n) - A061395(n).
a(n) = A334201(n) - A339896(n).
a(n) = A339893(A122111(n)).

A342657 The difference between floor(log_2(.)) of and the number of prime factors in A156552(n) (when counted with multiplicity).

Original entry on oeis.org

0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 2, 0, 3, 1, 1, 0, 2, 0, 3, 1, 3, 0, 3, 0, 4, 1, 3, 0, 2, 0, 3, 3, 5, 1, 1, 0, 7, 3, 3, 0, 4, 0, 5, 2, 5, 0, 4, 0, 2, 4, 6, 0, 3, 1, 5, 5, 7, 0, 4, 0, 9, 3, 2, 3, 4, 0, 6, 7, 4, 0, 3, 0, 10, 2, 7, 1, 5, 0, 5, 1, 11, 0, 3, 3, 11, 5, 3, 0, 2, 1, 8, 7, 11, 4, 4, 0, 3, 3, 3, 0, 5, 0, 7, 2
Offset: 2

Views

Author

Antti Karttunen, Mar 18 2021

Keywords

Crossrefs

Programs

  • PARI
    A156552(n) = {my(f = factor(n), p, p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res};
    A342657(n) = { my(u=A156552(n)); (#binary(u)-bigomega(u))-1; };

Formula

a(n) = (A252464(n)-A342655(n))-1 = (A325134(n)-A342655(n)) - 2.
a(p) = a(p^2) = 0 for all primes p. (Second part added Jul 27 2023)
a(A003961(n)) = a(2*A246277(n)) = a(n).
Showing 1-2 of 2 results.