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A306905 a(n) = A306898(n)/2. 2
1, 4, 6, 16, 20, 48, 70, 160, 270, 560, 1034, 2160, 4108, 8344, 16440, 33088, 65552, 131688, 262162, 525440, 1048740, 2099240, 4194326, 8393184, 16777300, 33562672, 67109418, 134234464, 268435484, 536904960, 1073741854, 2147549824, 4294969404 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
FORMULA
a(n) = n * A000013(n). - Seiichi Manyama, Jul 14 2023
MATHEMATICA
Table[DivisorSum[n, 2^#*EulerPhi[2 n/#] &]/2, {n, 33}] (* Michael De Vlieger, Dec 01 2019 *)
PROG
(PARI) a(n) = sumdiv(n, d, 2^(n/d-1)*eulerphi(2*d)); \\ Seiichi Manyama, Jul 14 2023
CROSSREFS
Sequence in context: A302119 A120542 A132344 * A097970 A044858 A323043
KEYWORD
nonn
AUTHOR
STATUS
approved

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Last modified June 16 19:52 EDT 2024. Contains 373432 sequences. (Running on oeis4.)