OFFSET
1,9
MATHEMATICA
b[n_, i_] := b[n, i] = If[n==0 || i==1, n, {q, r} = QuotientRemainder[n, i]; If[r == 0, q, 0] + Sum[b[n - i*j, i - 1], {j, 0, n/i}]];
a[n_] := n + DivisorSigma[0, n] + PartitionsP[n - 1] + b[n, n] -
Total[PartitionsP[Range[0, n]]] - DivisorSigma[1, n] - 1;
CROSSREFS
KEYWORD
nonn
AUTHOR
Omar E. Pol, Jan 16 2013
EXTENSIONS
a(49) corrected by Jean-François Alcover, Jun 05 2021
STATUS
approved