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%I #9 Aug 03 2023 16:46:22
%S 0,1,3,19,54,109,120,55,153,109,120,55,153,109,120,55,153,109,120,55,
%T 153,109,120,55,153,109,120,55,153,109,120,55,153,109,120,55,153,109,
%U 120,55,153,109,120,55,153,109,120,55,153,109,120,55,153,109,120,55,153
%N a(n+2) = sum_digits[a(n+1)] + sum_digits[a(n)] + sum_digits[a(n+1)]*sum_digits[a(n)], with a(0)=0, a(1)=1.
%C Period [153,109,120,55] after 6 terms. - _Georg Fischer_, Aug 22 2020
%p P:=proc(n)local a0,a1,i,k,w,x; a0:=0; a1:=1; print(a0);print(a1); for i from 1 by 1 to n do w:=0; k:=a0+a1; while k>0 do w:=w+k-(trunc(k/10)*10); k:=trunc(k/10); od; x:=0; k:=a1; while k>0 do x:=x+k-(trunc(k/10)*10); k:=trunc(k/10); od; a0:=a1; a1:=w+x+w*x; print(a1); od; end: P(100);
%t PadRight[{0,1,3,19,54},100,{153,109,120,55}] (* _Harvey P. Dale_, Aug 03 2023 *)
%Y Cf. A010077.
%K easy,nonn,base
%O 0,3
%A _Paolo P. Lava_ and _Giorgio Balzarotti_, Jan 30 2008
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