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Number of 10-digit numbers whose sum of digits is n.
1

%I #23 Jul 10 2017 04:26:20

%S 1,10,55,220,715,2002,5005,11440,24310,48619,92359,167815,293215,

%T 494725,808753,1284481,1986490,2997280,4419415,6376951,9015769,

%U 12502435,17021245,22769185,29948644,38757862,49379275,61966135,76628035,93416221,112309741,133203565,155899810,180103120

%N Number of 10-digit numbers whose sum of digits is n.

%C The 10-digit numbers distributed according to the sum of their digits n.

%C The sequence is symmetrical; a(n) = a(91 - n), 1 <= n <= 91.

%H Miquel Cerda, <a href="/A289380/b289380.txt">Table of n, a(n) for n = 1..90</a>

%F G.f.: (1 - x^10)^9*(x - x^10)/(1 - x)^10.

%e a(2)=10: 1000000001, 1000000010, 1000000100, 1000001000, 1000010000, 1000100000, 1001000000, 1010000000, 110000000, 200000000.

%t CoefficientList[Series[(1 - x^10)^9*(1 - x^9)/(1 - x)^10, {x, 0, 40}],

%t x] (* _Wesley Ivan Hurt_, Jul 09 2017 *)

%Y Cf. A071817 (3-digit numbers), A090579 (4-digit numbers), A090580 (5-digit numbers), A090581 (6-digit numbers), A278969 (7-digit numbers), A278971 (8-digit numbers), A289354 (9-digit numbers).

%K base,fini,full,nonn

%O 1,2

%A _Miquel Cerda_, Jul 04 2017