A043262 Sum of digits of n-th base 3 palindrome.

0, 1, 2, 2, 4, 2, 3, 4, 4, 5, 6, 2, 4, 6, 4, 6, 8, 2, 3, 4, 4, 5, 6, 6, 7, 8, 4, 5, 6, 6, 7, 8, 8, 9, 10, 2, 4, 6, 4, 6, 8, 6, 8, 10, 4, 6, 8, 6, 8, 10, 8, 10, 12, 2, 3, 4, 4, 5, 6, 6, 7, 8, 4, 5, 6, 6, 7, 8, 8, 9, 10, 6, 7, 8, 8, 9, 10, 10, 11, 12, 4, 5, 6, 6, 7, 8

Offset: 1

Author

Clark Kimberling

Keywords

• nonn
• base

Crossrefs

Cf. A014190 (base 3 palindromes)

Programs

Mathematica

Total/@Select[IntegerDigits[Range[0,2000],3],#==Reverse[#]&] (* Harvey P. Dale, Aug 08 2019 *)

Python

from gmpy2 import digits
def A043262(n):
    if n == 1: return 0
    y = 3*(x:=3**(len(digits(n>>1, 3))-1))
    return int((s:=digits(n-x,3))[-1])+(sum(int(d) for d in s[:-1])<<1) if nChai Wah Wu, Jul 24 2024