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

1,3

Links

Table of n, a(n) for n=1..86.

Mathematica

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

Prog

(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 n<x+y else sum(map(int, digits(n-y, 3)))<<1 # Chai Wah Wu, Jul 24 2024

Crossrefs

Cf. A014190 (base 3 palindromes)

Sequence in context: A103274 A046820 A356878 * A130860 A161535 A138785

Adjacent sequences: A043259 A043260 A043261 * A043263 A043264 A043265

Keyword

nonn,base

Author

Clark Kimberling

Status

approved