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 A278781 Numbers n such that A000041(n) is of the form 2^4 * k for odd k. 7
 15, 106, 122, 131, 136, 253, 295, 327, 339, 383, 412, 449, 465, 517, 520, 551, 580, 581, 599, 602, 632, 648, 669, 677, 776, 806, 815, 838, 904, 927, 1071, 1137, 1166, 1174, 1199, 1263, 1275, 1298, 1325, 1375, 1399, 1404, 1425, 1554, 1564, 1641, 1684, 1688 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers n such that A278478(n) = 4. Also numbers n such that A000041(n) has four times as many even divisors as odd divisors. LINKS Colin Barker, Table of n, a(n) for n = 1..600 FORMULA A000041(a(n)) = A278198(n). PROG (PARI) isok(n) = valuation(numbpart(n), 2)==4; select(n->isok(n), vector(2000, n, n)) CROSSREFS Cf. A000041, A278198, A278779, A278780, A278782, A278783, A278784. Positions of 4's in A278478. Sequence in context: A143727 A231327 A041426 * A275644 A074877 A293263 Adjacent sequences:  A278778 A278779 A278780 * A278782 A278783 A278784 KEYWORD nonn AUTHOR Colin Barker, Nov 28 2016 STATUS approved

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Last modified March 25 21:57 EDT 2019. Contains 321477 sequences. (Running on oeis4.)