A138470 Number of numbers less than n having a smaller sum of digits.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 3, 6, 9, 12, 15, 18, 21, 24, 27, 29, 6, 10, 14, 18, 22, 26, 30, 34, 37, 39, 10, 15, 20, 25, 30, 35, 40, 44, 47, 49, 15, 21, 27, 33, 39, 45, 50, 54, 57, 59, 21, 28, 35, 42, 49, 55, 60, 64, 67, 69, 28, 36, 44, 52, 59, 65

Offset

0,3

Comments

a(n) + A138471(n) + A138472(n) = n.

Links

R. Zumkeller, Table of n, a(n) for n = 0..1500

Index entries for Colombian or self numbers and related sequences

Example

a(42)=#{0,1,2,3,4,5,10,11,12,13,14,20,21,22,23,30,31,32,40,41}=20.

Maple

digitsum:=proc(n) options operator, arrow: add(convert(n, base, 10)[j], j=1.. nops(convert(n, base, 10))) end proc: a:=proc (n) local ct, j: ct:=0: for j from 0 to n-1 do if digitsum(j) < digitsum(n) then ct:=ct+1 else end if end do: ct end proc: seq(a(n), n=0..75); # Emeric Deutsch, Mar 31 2008

Crossrefs

Cf. A007953.

Sequence in context: A156207 A061486 A264600 * A325454 A112875 A113018

Adjacent sequences: A138467 A138468 A138469 * A138471 A138472 A138473

Keyword

nonn,base,look

Author

Reinhard Zumkeller, Mar 19 2008

Status

approved