OFFSET
1,12
COMMENTS
We can't just define this as number of pairs k, e with e > 0 that have sigma_e(k) = n, because sigma_e(1) = 1 for all e.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
a(28) = 2 because 28 = sigma_1(12) = 1+2+3+4+6+12 and also 28 = sigma_3(3) = 1^3+3^3.
PROG
(PARI) alist(n)=my(r=vector(n), s); r[1]=1; for(k=2, n, e=1; while((s=sigma(k, e))<=n, r[s]++; e++)); r
CROSSREFS
KEYWORD
nonn
AUTHOR
Franklin T. Adams-Watters, Apr 10 2016
STATUS
approved