A015986 Seven iterations of Reverse and Add are needed to reach a palindrome.

188, 190, 197, 287, 296, 386, 395, 485, 494, 584, 593, 683, 692, 782, 791, 881, 890, 980, 1394, 1484, 1574, 1664, 1754, 1844, 1898, 1934, 1988, 1992, 1994, 1999, 2393, 2483, 2573, 2663, 2753, 2843, 2897, 2933, 2987, 2991, 2993, 2998

Offset: 0

Author

Robert G. Wilson v

Keywords

• nonn
• base

Comments

The number of iterations starts at 1, so palindromes (cf. A002113) are not excluded. The corresponding sequence excluding palindromes is A065212.

Links

• Harvey P. Dale, Table of n, a(n) for n = 0..1000
• Index entries for sequences related to Reverse and Add!

Crossrefs

A002113, A065212.

Programs

Mathematica

sirapQ[n_]:=Boole[PalindromeQ/@Rest[NestList[#+IntegerReverse[#]&,n,7]]]=={0,0,0,0,0,0,1}; Select[Range[3000],sirapQ] (* Harvey P. Dale, May 11 2025 *)