A033648 Trajectory of 3 under map x->x + (x-with-digits-reversed).

3, 6, 12, 33, 66, 132, 363, 726, 1353, 4884, 9768, 18447, 92928, 175857, 934428, 1758867, 9447438, 17794887, 96644658, 182289327, 906271608, 1712444217, 8836886388, 17673772776, 85401510447, 159803020905, 668823329856, 1327746658722, 3606313135953, 7201626272016

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• base

Comments

Normally one stops as soon as a palindrome is reached.

A Reverse and Add! sequence.

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..1000 (first 251 terms from Reinhard Zumkeller)
• Index entries for sequences related to Reverse and Add!

Crossrefs

Cf. A006960, A001127, A033649, A033650, A033651.

Cf. A056964, A004086.

Row n=3 of A243238.

Programs

Haskell

a033648 n = a033648_list !! n
a033648_list = iterate a056964 3 -- Reinhard Zumkeller, Sep 22 2011

Maple

a:= proc(n) option remember; `if`(n=0, 3, (h-> h+ (s->
      parse(cat(s[-i]$i=1..length(s))))(""||h))(a(n-1)))
    end:
seq(a(n), n=0..40);  # Alois P. Heinz, Jun 18 2014

Mathematica

NestList[ # + FromDigits@Reverse@IntegerDigits@# &, 3, 29] (* Robert G. Wilson v, Dec 16 2005 *)