A118596 - OEIS

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A118596

Palindromes in base 5 (written in base 5).

0, 1, 2, 3, 4, 11, 22, 33, 44, 101, 111, 121, 131, 141, 202, 212, 222, 232, 242, 303, 313, 323, 333, 343, 404, 414, 424, 434, 444, 1001, 1111, 1221, 1331, 1441, 2002, 2112, 2222, 2332, 2442, 3003, 3113, 3223, 3333, 3443, 4004, 4114, 4224, 4334, 4444, 10001

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OFFSET

1,3

COMMENTS

Equivalently, palindromes k (written in base 10) such that 2*k is a palindrome. - Bruno Berselli, Sep 12 2018

LINKS

Table of n, a(n) for n=1..50.

MATHEMATICA

(* get NextPalindrome from A029965 *) Select[NestList[NextPalindrome, 0, 198], Max@IntegerDigits@# < 5 &] (* Robert G. Wilson v, May 09 2006 *)

Select[FromDigits/@IntegerDigits[Range[1000], 5], PalindromeQ] (* Fred Patrick Doty, Aug 12 2017 *)

PROG

(PARI) is(n)=if(n<5, return(n>=0)); my(d=digits(n)); vecmax(d)<5 && Vecrev(d)==d \\ Charles R Greathouse IV, Aug 22 2017

(Python)

from sympy import integer_log

from gmpy2 import digits

def A118596(n):

if n == 1: return 0

y = 5*(x:=5**integer_log(n>>1, 5)[0])

return int((s:=digits(n-x, 5))+s[-2::-1] if n<x+y else (s:=digits(n-y, 5))+s[::-1]) # Chai Wah Wu, Jun 14 2024

CROSSREFS

Cf. A029952, A057148, A118594, A118595, A118596, A118597, A118598, A118599, A118600, A002113.

Sequence in context: A104109 A066347 A367807 * A139763 A037396 A037432

Adjacent sequences: A118593 A118594 A118595 * A118597 A118598 A118599

KEYWORD

nonn,base

AUTHOR

Martin Renner, May 08 2006

EXTENSIONS

More terms from Robert G. Wilson v, May 09 2006

STATUS

approved