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A004092 Sum of digits of even numbers. 5
0, 2, 4, 6, 8, 1, 3, 5, 7, 9, 2, 4, 6, 8, 10, 3, 5, 7, 9, 11, 4, 6, 8, 10, 12, 5, 7, 9, 11, 13, 6, 8, 10, 12, 14, 7, 9, 11, 13, 15, 8, 10, 12, 14, 16, 9, 11, 13, 15, 17, 1, 3, 5 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
COMMENTS
a(n) >= A007953(n) / 5 with equality iff n is in A169964 (see Diophante link). - Bernard Schott, Apr 29 2023
LINKS
Diophante, A1762, Des chiffres à la moulinette (in French).
FORMULA
a(n) = 2n - 9*Sum_{k=1..1+floor(log_10(2n))} floor( n/(5*10^(k-1)) ). - Anthony Browne, Jun 18 2016
a(n) = A007953(2n). - Alois P. Heinz, Apr 11 2018
MATHEMATICA
Table[Sum[DigitCount[2*n][[i]]*i, {i, 9}], {n, 0, 100}] (* G. C. Greubel, Jun 19 2016 *)
PROG
(PARI) a(n)=sumdigits(2*n) \\ Charles R Greathouse IV, Jun 19 2016
CROSSREFS
Sequence in context: A146082 A169909 A180592 * A133311 A088402 A077492
KEYWORD
nonn,base,easy
AUTHOR
N. J. A. Sloane, Dec 11 1996
STATUS
approved

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Last modified March 29 08:59 EDT 2024. Contains 371268 sequences. (Running on oeis4.)