A076663 a(n) = sum of sigma(e) where e ranges over all non-divisors of n that are between 1 and n.

0, 0, 3, 4, 14, 13, 32, 30, 51, 59, 86, 72, 126, 129, 154, 163, 219, 205, 276, 262, 326, 355, 406, 361, 484, 504, 546, 561, 659, 622, 761, 737, 840, 883, 944, 900, 1097, 1112, 1177, 1160, 1341, 1300, 1479, 1465, 1560, 1658, 1757, 1645, 1921, 1928, 2057, 2085

Offset

1,3

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Formula

a(n) = A024916(n) - A007429(n). - Robert Israel, Oct 27 2024

Maple

N:= 1000: # for a(1) .. a(N)
S:= [seq(numtheory:-sigma(n), n=1..N)]:
SS:= ListTools:-PartialSums(S):
seq(SS[n] - add(S[d], d = numtheory:-divisors(n)), n=1..N); # Robert Israel, Oct 27 2024

Mathematica

f[n_] := Module[{s, i}, s = 0; For[i = 1, i < n, i++, If[Mod[n, i] != 0, s = s + DivisorSigma[1, i]]]; s]; Table[f[i], {i, 1, 100}]

Crossrefs

Cf. A000203, A007429, A024916.

Sequence in context: A337297 A220846 A009286 * A277933 A278953 A280608

Adjacent sequences: A076660 A076661 A076662 * A076664 A076665 A076666

Keyword

nonn

Author

Joseph L. Pe, Oct 24 2002

Status

approved