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 A152573 The smallest superharmonic number with index n. 0
 6, 30, 102, 186, 1146, 762, 8022, 5334, 35526, 23622, 145542, 49146, 540606, 344022, 2309862, 786426, 4718586, 3145722, 33030102, 22020054, 146276166, 97517382, 599260422, 399506694 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(n) is the smallest number s such that sigma(s) divides s^n*tau(s). In short: a(n) is the smallest supersymmetric number with index n. LINKS Graeme L. Cohen, Superharmonic numbers, Math. Comp. 78 (2009), 421-429. FORMULA a(n)= min s: A000203(s) | s^n*A000005(s). EXAMPLE For n=1, a(1)=6 because sigma(6)=12 divides 6^1*tau(6)=6*4=24. PROG (PARI) isharmonic(val, index) = ((val^index*numdiv(val) % sigma(val)) == 0) a(n) = {val = 2; ok = 0; until (ok, if (isharmonic(val, n), if (n == 1, ok = 1, indi = 1; while (! isharmonic(val, indi), indi++); if (indi == n, ok = 1); ); ); if (! ok, val++); ); return (val); } \\ Michel Marcus, Jul 24 2013 CROSSREFS Cf. A001599. Sequence in context: A101855 A101375 A074007 * A258723 A225382 A245804 Adjacent sequences:  A152570 A152571 A152572 * A152574 A152575 A152576 KEYWORD nonn AUTHOR R. J. Mathar, Dec 08 2008 STATUS approved

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Last modified May 28 14:47 EDT 2020. Contains 334684 sequences. (Running on oeis4.)