A135207 a(n)=Sum_digits{n^Sum_digits[a(n-1)]}, with a(0)=1.

1, 1, 2, 9, 19, 40, 18, 28, 37, 45, 1, 2, 9, 46, 67, 81, 64, 55, 54, 73, 7, 36, 55, 49, 99, 109, 64, 63, 64, 34, 18, 55, 76, 81, 73, 73, 72, 82, 79, 90, 19, 49, 99, 136, 82, 63, 64, 70, 54, 73, 40, 27, 82, 82, 72, 82, 70, 72, 91, 49, 36, 64, 91, 99, 145, 79, 126, 82, 58, 126, 28

Offset: 0

Author

Paolo P. Lava and Giorgio Balzarotti, Dec 03 2007

Keywords

• easy
• nonn

Links

• Harvey P. Dale, Table of n, a(n) for n = 0..1000

Crossrefs

Cf. A047912, A066588, A108827.

Programs

Maple

P:=proc(n) local a,i,k,w; a:=1; print(a); for i from 1 by 1 to n do w:=0; k:=a; while k>0 do w:=w+k-(trunc(k/10)*10); k:=trunc(k/10); od; k:=i^w; w:=0; while k>0 do w:=w+k-(trunc(k/10)*10); k:=trunc(k/10); od; a:=w; print(w); od; end: P(100);

Mathematica

nxt[{n_,a_}]:={n+1,Total[IntegerDigits[(n+1)^Total[IntegerDigits[a]]]]}; NestList[nxt,{0,1},70][[;;,2]] (* Harvey P. Dale, Nov 03 2024 *)