OFFSET
1,2
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..10082
FORMULA
a(1) = 1; for n > 1, a(n) = A000005(2*n-1) + a(n-1).
a(n) ~ n * (log(n) + 2*gamma + 3*log(2) - 1)/2, where gamma is Euler's constant (A001620). - Amiram Eldar, Jan 14 2024
MATHEMATICA
FoldList[DivisorSigma[0, 2*#2-1]+#1&, 1, Range[2, 62]] (* Ivan N. Ianakiev, Oct 24 2015 *)
Accumulate[Table[DivisorSigma[0, 2*n-1], {n, 1, 100}]] (* Vaclav Kotesovec, Jan 14 2019 *)
PROG
(Scheme, with memoization-macro definec)
(PARI) lista(nn) = {s = 0; forstep (n=1, nn, 2, s += numdiv(n); print1(s, ", "); ); } \\ Michel Marcus, Oct 12 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Oct 12 2015
STATUS
approved