A048572 a(n) = sum of digits of a(n-1)*a(n-2).

1, 2, 2, 4, 8, 5, 4, 2, 8, 7, 11, 14, 10, 5, 5, 7, 8, 11, 16, 14, 8, 4, 5, 2, 1, 2, 2, 4, 8, 5, 4, 2, 8, 7, 11, 14, 10, 5, 5, 7, 8, 11, 16, 14, 8, 4, 5, 2, 1, 2, 2, 4, 8, 5, 4, 2, 8, 7, 11, 14, 10, 5, 5, 7, 8, 11, 16, 14, 8, 4, 5, 2

Offset: 1

Author

David Johnson-Davies

Keywords

• nonn
• easy
• nice
• base

Comments

This sequence is periodic with period 24. - T. D. Noe, Feb 15 2008

Links

• Index entries for linear recurrences with constant coefficients, signature (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1).

Programs

Mathematica

Nest[Append[#,Total[IntegerDigits[Last[#]#[[-2]]]]]&,{1,2},80]  (* Harvey P. Dale, Apr 21 2011 *)
PadRight[{},100,{1,2,2,4,8,5,4,2,8,7,11,14,10,5,5,7,8,11,16,14,8,4,5,2}] (* Harvey P. Dale, Jan 18 2015 *)

Formula

a(n) = a(n-24) for n >= 25. - Wesley Ivan Hurt, Mar 09 2023