A070312 a(1) = a(2) = 1; a(n) = a(n-1) + concatenation of a(n-2) and a(n-1).

1, 1, 12, 124, 12248, 12424496, 1224824848992, 124244962449649697984, 1224824848992248489924899299395968, 1242449624496496979842449649697984496979849798598791936

Offset

1,3

Links

Harvey P. Dale, Table of n, a(n) for n = 1..16

Example

a(4) = a(3) + concatenation of a(2) and a(3) = 12 + 112 = 124.

Mathematica

a[n_] := (a[n - 1] + FromDigits[ Join[ IntegerDigits[ a[n - 2]], IntegerDigits[ a[n - 1]]]]); a[1] = a[2] = 1; Table[ a[n], {n, 1, 10}]
nxt[{a_, b_}]:={b, b+a*10^IntegerLength[b]+b}; NestList[nxt, {1, 1}, 10][[;; , 1]] (* Harvey P. Dale, Oct 20 2023 *)

Crossrefs

Sequence in context: A331396 A209041 A155595 * A153427 A356822 A178626

Adjacent sequences: A070309 A070310 A070311 * A070313 A070314 A070315

Keyword

base,nonn

Author

Joseph L. Pe, May 11 2002

Extensions

Edited by Robert G. Wilson v, May 14 2002

Status

approved