A134268 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.

0, 1, 3, 19, 54, 109, 120, 55, 153, 109, 120, 55, 153, 109, 120, 55, 153, 109, 120, 55, 153, 109, 120, 55, 153, 109, 120, 55, 153, 109, 120, 55, 153, 109, 120, 55, 153, 109, 120, 55, 153, 109, 120, 55, 153, 109, 120, 55, 153, 109, 120, 55, 153, 109, 120, 55, 153

Offset: 0

Author

Paolo P. Lava and Giorgio Balzarotti, Jan 30 2008

Keywords

• easy
• nonn
• base

Comments

Period [153,109,120,55] after 6 terms. - Georg Fischer, Aug 22 2020

Crossrefs

Cf. A010077.

Programs

Maple

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);

Mathematica

PadRight[{0,1,3,19,54},100,{153,109,120,55}] (* Harvey P. Dale, Aug 03 2023 *)