OFFSET
2,5
COMMENTS
A152454 is the irregular triangle in which row n lists the numbers whose proper divisors sum to n.
LINKS
Michel Marcus, Table of n, a(n) for n = 2..10001
EXAMPLE
A152454 begins as []; [4]; [9]; []; [6, 25]; [8]; [10, 49]...
so sequence begins 0, 0, 0, 0, 19, 0, 39, ...
PROG
(PARI) lista(nn) = my(v = vector(nn, k, [])); forcomposite (i=1, nn^2, my(x=sigma(i)-i); if (x <= nn, v[x] = concat(v[x], i)); ); vector(nn-1, k, k++; if (#v[k], vecmax(v[k]) - vecmin(v[k])));
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Marcus, Oct 28 2023
STATUS
approved