A178713 - OEIS

%I #13 Jan 06 2019 04:05:46

%S 0,1,2,4,10,11,12,14,21,33,41,101,110,111,112,114,121,133,141,203,211,

%T 223,230,232,300,302,313,320,322,331,411,1003,1011,1023,1030,1032,

%U 1101,1110,1111,1112,1114,1121,1133,1141,1203,1211,1223,1230,1232,1300,1302,1313,1320,1322,1331,1411,2000

%N Numbers k such that the sum of the subfactorial of the decimal digits of k is a square.

%e 3656 is a term because !3 + !6 + !5 + !6 = 2 + 265 + 44 + 265 = 576 = 24^2.

%p A000166s := proc(n) local dgs; dgs := convert(n,base,10) ; add(A000166(d),d=dgs) ; end proc:

%p isA178713  := proc(n)issqr(A000166s(n)) ; end proc:

%p for n from 0 to 2000 do if isA178713(n) then printf("%d,",n); end if; end do: # _R. J. Mathar_, Jan 06 2011

%Y Cf. A000166.

%K nonn,base,less

%O 1,3

%A _Michel Lagneau_, Dec 26 2010