A001127 Trajectory of 1 under map x->x + (x-with-digits-reversed).

1, 2, 4, 8, 16, 77, 154, 605, 1111, 2222, 4444, 8888, 17776, 85547, 160105, 661166, 1322332, 3654563, 7309126, 13528163, 49710694, 99312488, 187733887, 976071668, 1842242347, 9274664828, 17559329557, 93151725128, 175304440267, 937348843838, 1775697687577

Offset: 0

Author

N. J. A. Sloane, Jun 05 2002

Keywords

• nonn
• base
• easy
• nice

Comments

Normally one stops as soon as a palindrome is reached.

A Reverse and Add! sequence.

Trajectories of 25, 34, 43, 52, 59, 61, 68, 70, 86, 95, ..., merge into this sequence. - Robert G. Wilson v, Dec 16 2005

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, A023108, A033648, A033649, A033650, A033651.

Cf. A056964, A004086.

Row n=1 of A243238.

Programs

Haskell

a001127 n = a001127_list !! n
a001127_list = iterate a056964 1 -- Reinhard Zumkeller, Sep 22 2011

Maple

a:= proc(n) option remember; `if`(n=0, 1, (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@# &, 1, 30] (* Robert G. Wilson v, Dec 16 2005 *)
NestList[#+IntegerReverse[#]&,1,30] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Nov 19 2019 *)