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A324122
a(n) = sigma(n) - gcd(n*d(n), sigma(n)), where d(n) = number of divisors of n (A000005) and sigma(n) = sum of divisors of n (A000203).
4
0, 2, 2, 6, 4, 0, 6, 14, 12, 16, 10, 24, 12, 16, 12, 30, 16, 36, 18, 36, 28, 32, 22, 48, 30, 40, 36, 0, 28, 48, 30, 60, 36, 52, 44, 90, 36, 56, 52, 80, 40, 48, 42, 72, 72, 64, 46, 120, 54, 90, 60, 96, 52, 96, 68, 112, 76, 88, 58, 144, 60, 88, 102, 126, 80, 96, 66, 120, 84, 128, 70, 192, 72, 112, 122, 136, 92, 144, 78, 184, 120, 124, 82
OFFSET
1,2
FORMULA
a(n) = A000203(n) - A324121(n) = A000203(n) - gcd(A000203(n), A038040(n)).
PROG
(PARI) A324122(n) = (sigma(n) - gcd(sigma(n), n*numdiv(n)));
CROSSREFS
Cf. A001599 (positions of zeros).
Sequence in context: A372576 A276085 A334870 * A374408 A324349 A092384
KEYWORD
nonn
AUTHOR
Antti Karttunen, Feb 15 2019
STATUS
approved