A138828 - OEIS

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A138828

Sum of digits of n-th even perfect number.

6, 10, 19, 19, 28, 64, 55, 73, 190, 235, 289, 352, 1405, 1711, 3520, 5833, 5968, 8821, 11548, 11791, 26317, 27298, 30232, 53740, 58960, 62956, 120898, 233722, 299314, 356860, 585478, 2048248, 2329372, 3405232, 3789352, 8056495, 8186041, 18894079, 36485416, 56880973, 65115946, 70334902, 82384129

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Ivan Panchenko, Table of n, a(n) for n = 1..47

Omar E. Pol, Determinacion geometrica de los numeros primos y perfectos.

FORMULA

a(n) = A007953(A000396(n)). - R. J. Mathar, May 22 2008 [This assumes that all perfect numbers are even. - Ivan Panchenko, Aug 16 2018]

MATHEMATICA

a[n_] := Block[{e, p, mpe = MersennePrimeExponent@n}, Plus @@ IntegerDigits[(2^mpe - 1) 2^(mpe - 1)]]; Array[a, 44] (* Robert G. Wilson v, Aug 06 2018 *)

Total[IntegerDigits[#]]&/@Table[PerfectNumber[n], {n, 43}] (* Requires Mathematica version 10 or later *) (* The program may take a long time to run *) (* Harvey P. Dale, Feb 07 2019 *)

CROSSREFS

Cf. A000396, A007605, A066538, A138127.

Sequence in context: A307458 A338450 A287273 * A109312 A257858 A095985

Adjacent sequences: A138825 A138826 A138827 * A138829 A138830 A138831

KEYWORD

base,nonn

AUTHOR

Omar E. Pol, Apr 01 2008

EXTENSIONS

More terms from R. J. Mathar, May 22 2008

a(15)-a(38) from Donovan Johnson, Nov 09 2010

Definition changed (inserting the word "even") and a(39)-a(43) added by Ivan Panchenko, Aug 06 2018

STATUS

approved