A015976 One iteration of Reverse and Add is needed to reach a palindrome.

1, 2, 3, 4, 10, 11, 12, 13, 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 26, 27, 29, 30, 31, 32, 33, 34, 35, 36, 38, 40, 41, 42, 43, 44, 45, 47, 50, 51, 52, 53, 54, 56, 60, 61, 62, 63, 65, 70, 71, 72, 74, 80, 81, 83, 90, 92, 100, 101, 102, 103, 104, 105, 106

Offset: 1

Author

Robert G. Wilson v

Keywords

• nonn
• base
• look

Comments

The number of iterations starts at 1, so palindromes (cf. A002113) are not excluded. The corresponding sequence excluding palindromes is A065206.

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
• Index entries for sequences related to Reverse and Add!

Crossrefs

Cf. A002113, A065206.

Programs

Haskell

a015976 n = a015976_list !! (n-1)
a015976_list = filter ((== 1) . a136522 . a056964) [1..]
-- Reinhard Zumkeller, Oct 14 2011

Mathematica

rev[n_] := FromDigits[Reverse[IntegerDigits[n]]]; Select[Range[106], rev[x = # + rev[#]] == x &] (* Jayanta Basu, Jul 24 2013 *)
Select[Range[120],PalindromeQ[#+IntegerReverse[#]]&] (* Harvey P. Dale, Jul 04 2022 *)

Extensions

Offset corrected by Reinhard Zumkeller, Oct 14 2011