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A366110
a(n) is the difference between the maximum and minimum number whose proper divisors sum to n, or 0 if there is no such number.
2
0, 0, 0, 0, 19, 0, 39, 0, 0, 0, 0, 8, 147, 17, 14, 16, 0, 12, 327, 73, 18, 28, 0, 48, 0, 64, 0, 72, 0, 189, 903, 202, 0, 160, 0, 168, 0, 0, 37, 328, 1651, 387, 1767, 280, 34, 364, 0, 476, 54, 448, 0, 432, 2767, 677, 0, 604, 0, 432, 0, 528, 3603, 753, 66, 826, 0, 768, 0, 720, 0
OFFSET
2,5
COMMENTS
A152454 is the irregular triangle in which row n lists the numbers whose proper divisors sum to n.
LINKS
FORMULA
a(n) = A135244(n) - A070015(n).
a(A005114(n)) = a(A057709(n)) = 0.
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