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A043262
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Sum of digits of n-th base 3 palindrome.
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0
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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
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OFFSET
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1,3
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LINKS
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MATHEMATICA
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Total/@Select[IntegerDigits[Range[0, 2000], 3], #==Reverse[#]&] (* Harvey P. Dale, Aug 08 2019 *)
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PROG
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(Python)
from gmpy2 import digits
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
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CROSSREFS
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KEYWORD
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nonn,base,changed
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AUTHOR
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STATUS
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approved
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