A329036 - OEIS

A329036

Number of common divisors of n and A122111(n).

1, 2, 1, 1, 1, 4, 1, 1, 3, 2, 1, 2, 1, 2, 2, 1, 1, 2, 1, 6, 2, 2, 1, 2, 1, 2, 1, 3, 1, 8, 1, 1, 2, 2, 1, 2, 1, 2, 2, 3, 1, 4, 1, 3, 2, 2, 1, 2, 1, 2, 2, 3, 1, 1, 1, 8, 2, 2, 1, 4, 1, 2, 1, 1, 1, 4, 1, 3, 2, 4, 1, 2, 1, 2, 6, 3, 1, 4, 1, 3, 1, 2, 1, 12, 1, 2, 2, 4, 1, 4, 1, 3, 2, 2, 1, 2, 1, 1, 1, 1, 1, 4, 1, 4, 4

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OFFSET

1,2

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..65537

Index entries for sequences computed from indices in prime factorization

FORMULA

a(n) = A000005(A280491(n)) = A000005(gcd(n, A122111(n))).

a(n) = 1+A001222(A329042(n)) = 1+A001222(A329043(n)).

PROG

(PARI)

A064989(n) = {my(f); f = factor(n); if((n>1 && f[1, 1]==2), f[1, 2] = 0); for (i=1, #f~, f[i, 1] = precprime(f[i, 1]-1)); factorback(f)};