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 A309531 a(n) = Sum_{k=2..n} (-1)^k * A240236(n, k). 3
 1, 1, 0, 0, 2, 2, -3, 1, 5, 5, -2, -2, 4, 10, -6, -6, 1, 1, -8, 0, 10, 10, -16, -8, 4, 18, 7, 7, 13, 13, -19, -7, 9, 19, -11, -11, 7, 21, -15, -15, -5, -5, -20, 10, 32, 32, -36, -24, -1, 17, 0, 0, 18, 32, -14, 6, 34, 34, -23, -23, 7, 45, -29, -13, 5, 5, -16, 8, 30, 30, -66 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,5 LINKS Seiichi Manyama, Table of n, a(n) for n = 2..1000 FORMULA a(n) = a(n-1) if and only if n is an odd prime. EXAMPLE a(2) = 1. a(3) = 2 - 1 = 1. a(4) = 1 - 2 + 1 = 0. a(5) = 2 - 3 + 2 - 1 = 0. a(6) = 2 - 2 + 3 - 2 + 1 = 2. PROG (PARI) {a(n) = sum(k=2, n, (-1)^k*sumdigits(n, k))} CROSSREFS Cf. A000040, A043306, A065091, A240236. Sequence in context: A028507 A096226 A155980 * A215222 A219865 A016539 Adjacent sequences:  A309528 A309529 A309530 * A309532 A309533 A309534 KEYWORD sign,base AUTHOR Seiichi Manyama, Aug 06 2019 STATUS approved

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Last modified September 21 19:57 EDT 2020. Contains 337273 sequences. (Running on oeis4.)