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 A306898 a(n) = Sum_{d|n} 2^d*phi(2*n/d). 4
 2, 8, 12, 32, 40, 96, 140, 320, 540, 1120, 2068, 4320, 8216, 16688, 32880, 66176, 131104, 263376, 524324, 1050880, 2097480, 4198480, 8388652, 16786368, 33554600, 67125344, 134218836, 268468928, 536870968, 1073809920, 2147483708, 4295099648, 8589938808, 17180131456, 34359739120, 68720011776 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Michael De Vlieger, Table of n, a(n) for n = 1..3321 Dennis S. Bernstein, Omran Kouba, Counting Colorful Necklaces and Bracelets in Three Colors, arXiv:1901.10703 [math.CO], 2019. MAPLE See A306888. MATHEMATICA Table[DivisorSum[n, 2^# *EulerPhi[2 n/#] &], {n, 36}] (* Michael De Vlieger, Mar 18 2019 *) PROG (PARI) a(n) = sumdiv(n, d, 2^d*eulerphi(2*n/d)); \\ Michel Marcus, Mar 16 2019 CROSSREFS Cf. A306888, A306896. Sequence in context: A047174 A048074 A126775 * A069185 A037197 A125712 Adjacent sequences:  A306895 A306896 A306897 * A306899 A306900 A306901 KEYWORD nonn AUTHOR Michael De Vlieger and N. J. A. Sloane, Mar 15 2019 STATUS approved

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Last modified December 13 23:14 EST 2019. Contains 329974 sequences. (Running on oeis4.)