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A004155 Sum of digits of n-th odd number. 1
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, 10, 12, 14, 16, 18, 2, 4, 6, 8, 10, 3, 5, 7, 9, 11, 4, 6, 8, 10, 12, 5 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..10000

FORMULA

a(n) = 2n - 1 - 9*Sum_{k=1..1+floor(log_10(2n-1))} floor( (n-1)/(5*10^(k-1)) ). - Anthony Browne, Jun 18 2016

a(n) = A004092(n+5). - G. C. Greubel, Jun 19 2016

MATHEMATICA

Table[Sum[DigitCount[2*n + 1][[i]]*i, {i, 9}], {n, 0, 100}] (* G. C. Greubel, Jun 19 2016 *)

PROG

(PARI) a(n)=sumdigits(2*n+1) \\ Charles R Greathouse IV, Jun 19 2016

CROSSREFS

Cf. A004092.

Sequence in context: A225985 A032764 A131669 * A163125 A167047 A065271

Adjacent sequences:  A004152 A004153 A004154 * A004156 A004157 A004158

KEYWORD

nonn,base,easy

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified October 23 22:42 EDT 2019. Contains 328378 sequences. (Running on oeis4.)