OFFSET
2,3
COMMENTS
LINKS
Robert Israel, Table of n, a(n) for n = 2..10000
EXAMPLE
12=2*2*3 so a(12) = 2 + 2*2 + 2*3 + 3 = 15.
MAPLE
f:= proc(n) local L, m;
L:= sort(map(t -> t[1]$t[2], ifactors(n)[2]));
m:= nops(L);
add(mul(L[i], i=1..j)+mul(L[i], i=j+1..m), j=1..m-1)
end proc:
map(f, [$2..100]);
PROG
(PARI) conv(n) = {my(f=factor(n), v=vector(bigomega(n)), k=1); for (i=1, #f~, for (j=1, f[i, 2], v[k] = f[i, 1]; k++; ); ); v; }
a(n) = my(v=conv(n)); sum(j=1, #v-1, prod(k=1, j, v[k])) + sum(j=2, #v, prod(k=j, #v, v[k])); \\ Michel Marcus, Dec 04 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, Dec 04 2020
STATUS
approved