A152985 Sum of proper divisors minus the number of proper divisors of the square A000290(n).

0, 1, 2, 11, 4, 47, 6, 57, 36, 109, 10, 245, 12, 195, 170, 247, 16, 509, 18, 547, 292, 439, 22, 1055, 152, 597, 358, 969, 28, 1895, 30, 1013, 632, 985, 534, 2431, 36, 1215, 850, 2317, 40, 3397, 42, 2173, 1712, 1747, 46, 4313, 396, 2953, 1382, 2955, 52, 4715, 1090, 4083

Offset: 1

Author

Omar E. Pol, Dec 21 2008

Keywords

• nonn
• look

Links

• B. D. Swan, Table of n, a(n) for n=1,...,50000

Crossrefs

Cf. A000005, A000203, A000290, A001065, A032741, A152770.

Programs

PARI

a(n) = sigma(n^2) - n^2 - (numdiv(n^2) - 1); \\ Michel Marcus, Jan 28 2014

Formula

a(n) = A001065(A000290(n)) - A032741(A000290(n)) = A152770(A000290(n)).