A348968 - OEIS

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A348968

a(n) = gcd(n, A099377(n)), where A099377(n) is the numerator of the harmonic mean of the divisors of n.

1, 2, 3, 4, 5, 2, 7, 8, 9, 10, 11, 6, 13, 7, 5, 16, 17, 18, 19, 20, 21, 22, 23, 8, 25, 26, 27, 1, 29, 10, 31, 32, 11, 34, 35, 36, 37, 38, 39, 8, 41, 7, 43, 22, 45, 23, 47, 24, 49, 50, 17, 52, 53, 18, 55, 56, 57, 58, 59, 30, 61, 31, 63, 64, 65, 11, 67, 68, 23, 35, 71, 72, 73, 74, 75, 38, 77, 26, 79, 80, 81, 82, 83, 3

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..84.

FORMULA

a(n) = gcd(n, A099377(n)) = gcd(n, A348510(n)) = gcd(A099377(n), A348510(n)).

a(n) = n / A348969(n).

a(n) = A099377(n) / A057021(n). [Apparently, holds at least up to n = 2^25]

PROG

(PARI)

A003961(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };