OFFSET
0,3
COMMENTS
Different from A016135.
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..961 (terms n = 1..31 from Laurent Desnogues)
Project Euler, Problem 377: Sum of digits, experience 13
Tadao Takaoku, A two-level algorithm for generating multiset permutations, RIMS Kokyuroku 1644 (2009), pp. 95-109.
Index entries for linear recurrences with constant coefficients, signature (11,1,-9,-19,-29,-39,-49,-59,-69,-90,-80,-70,-60,-50,-40,-30,-20,-10).
FORMULA
G.f.: x*(9*x^8 + 8*x^7 + 7*x^6 + 6*x^5 + 5*x^4 + 4*x^3 + 3*x^2 + 2*x + 1)/((x^9 + x^8 + x^7 + x^6 + x^5 + x^4 + x^3 + x^2 + x - 1)*(10*x^9 + 10*x^8 + 10*x^7 + 10*x^6 + 10*x^5 + 10*x^4 + 10*x^3 + 10*x^2 + 10*x - 1)). - Yurii Ivanov, Jul 06 2021
EXAMPLE
2 and 11 are the only numbers without 0's which have digit sum 2, so a(2) = 2 + 11 = 13.
MAPLE
b:= proc(n) option remember; `if`(n=0, [1, 0], add((p->
[p[1], p[2]*10+p[1]*d])(b(n-d)), d=1..min(n, 9)))
end:
a:= n-> b(n)[2]:
seq(a(n), n=0..23); # Alois P. Heinz, Feb 19 2020
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Laurent Desnogues and Charles R Greathouse IV, Apr 02 2012
EXTENSIONS
a(0)=0 prepended by Alois P. Heinz, Feb 19 2020
STATUS
approved