A004155 Sum of digits of n-th odd number.

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

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, A007953.

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