A388978 a(n) = A326128(n) * A389077(n).

0, 0, 0, 9, 0, 0, 0, 60, 40, 0, 0, 252, 0, 0, 0, 585, 0, 736, 0, 510, 0, 0, 0, 1620, 168, 0, 624, 966, 0, 0, 0, 3540, 0, 0, 0, 6195, 0, 0, 0, 3300, 0, 0, 0, 1716, 2640, 0, 0, 14220, 528, 3744, 0, 2496, 0, 11232, 0, 6300, 0, 0, 0, 12330, 0, 0, 4816, 22869, 0, 0, 0, 3570, 0, 0, 0, 39340, 0, 0, 6624, 4674, 0, 0, 0

Offset

1,4

Links

Antti Karttunen, Table of n, a(n) for n = 1..20000

Index entries for sequences computed from indices in prime factorization.

Index entries for sequences related to sigma(n).

Formula

a(n) = (n-A007913(n)) * (A000203(A003961(n))-A007913(A003961(n))-A003961(n)).

a(n) = A341528(n) + A191002(A007913(n)) - A191002(n) - n*A007913(A003961(n)) - A003973(n)*A007913(n) + A007913(n)*A003961(n).

a(n) <= A388979(n).

Prog

(PARI)
A003961(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
A388978(n) = { my(u=A003961(n)); ((n-core(n)) * (sigma(u)-core(u)-u)); };

Crossrefs

Cf. A000203, A003961, A003973, A007913, A191002, A388979.

Cf. also A341528 & A341529, and A388976 & A388977.

Sequence in context: A036483 A353803 A275153 * A019313 A392846 A276999

Adjacent sequences: A388975 A388976 A388977 * A388979 A388980 A388981

Keyword

nonn

Author

Antti Karttunen, Sep 23 2025

Status

approved