A117828 Start with 1 and repeatedly reverse the decimal digits and add 4 to get the next term.

1, 5, 9, 13, 35, 57, 79, 101, 105, 505, 509, 909, 913, 323, 327, 727, 731, 141, 145, 545, 549, 949, 953, 363, 367, 767, 771, 181, 185, 585, 589, 989, 993, 403, 308, 807, 712, 221, 126, 625, 530, 39, 97, 83, 42, 28, 86, 72, 31, 17, 75, 61, 20, 6, 10, 5, 9, 13, 35, 57, 79, 101, 105, 505, 509, 909, 913, 323, 327, 727, 731

Offset: 1

Author

Luc Stevens (lms022(AT)yahoo.com), Apr 06 2006

Keywords

• nonn
• base
• easy

Links

• N. J. A. Sloane and others, Sequences of RADD type, OEIS wiki.
• Index entries for linear recurrences with constant coefficients, signature (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1).

Crossrefs

Cf. A117827, A117829, A117830.

Programs

Maple

read transforms; t1:=[1]; for n from 1 to 80 do t1:=[op(t1),4+digrev(t1[n])]; od: # N. J. A. Sloane

Mathematica

f[n_] := 4 + FromDigits@ Reverse@ IntegerDigits@n; NestList[ f@# &, 1, 57] (* and *)
(* to view the cycle *) NestWhileList[ f@# &, 1, UnsameQ, All] (* Robert G. Wilson v, May 09 2006 *)

PARI

a(n)=if(n>1, my(t=6); for(k=1,n%54, t=fromdigits(Vecrev(digits(t)))+4); t, 1) \\ Charles R Greathouse IV, Nov 07 2016

Formula

After one step enters a cycle of length 54: see A117827, A117830.