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%I #7 Mar 30 2012 18:36:00
%S 9,11,12,13,14,15,16,18,19,21,22,25,26,28,48,51,57,60,70,72,74,78,80,
%T 81,82,86,89,92,103,109,111,114,120,125,128,130,131,142,145,146,151,
%U 155,157,159,164,168,169,179,183,185,186,191,195,197,200,205,210,211
%N Numbers n such that (sum of digits of n!!) / 9 is prime.
%C If n = 9 and n >10, then (sum of digits of n!!) / 9 is an integer (see A120390).
%F n such that A120390(n) prime.
%e For n = 9, 9!! = 945, and (9+4+5)/9 = 2 is prime.
%t lst={}; Do[If[PrimeQ[Sum[DigitCount[n!!][[i]]*i/9,{i,1,9}]], AppendTo[lst, n]], {n,1,300}]; lst
%Y Cf. A006882, A120390.
%K nonn,base
%O 1,1
%A _Michel Lagneau_, Dec 23 2011