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 A067558 Sum of squares of proper divisors of n. 14
 0, 1, 1, 5, 1, 14, 1, 21, 10, 30, 1, 66, 1, 54, 35, 85, 1, 131, 1, 146, 59, 126, 1, 274, 26, 174, 91, 266, 1, 400, 1, 341, 131, 294, 75, 615, 1, 366, 179, 610, 1, 736, 1, 626, 341, 534, 1, 1106, 50, 755, 299, 866, 1, 1184, 147, 1114, 371, 846, 1, 1860, 1, 966, 581, 1365 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 COMMENTS a(n) = A001157(n) - n^2. a(n) = 1 if and only if n is prime. LINKS T. D. Noe, Table of n, a(n) for n=1..10000 FORMULA Dirichlet g.f.: zeta(s-2)*(zeta(s) - 1). - Ilya Gutkovskiy, Sep 08 2016 EXAMPLE a(12) = 1^2 + 2^2 + 3^2 + 4^2 + 6^2 = 1 + 4 + 9 + 16 + 36 = 66. MATHEMATICA Table[DivisorSigma[2, n] - n^2, {n, 1, 64}] (* Jean-François Alcover, Mar 01 2019 *) PROG (PARI) a(n)=sigma(n, 2)-n^2 \\ Charles R Greathouse IV, Dec 07 2011 CROSSREFS Cf. A001157, A032741. Sequence in context: A300291 A174504 A270654 * A104792 A120393 A094368 Adjacent sequences: A067555 A067556 A067557 * A067559 A067560 A067561 KEYWORD nonn AUTHOR Reinhard Zumkeller, Jan 29 2002 STATUS approved

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Last modified March 22 17:42 EDT 2023. Contains 361432 sequences. (Running on oeis4.)