Reciprocal Sum of Palindromes
Phakhinkon Phunphayap and Prapanpong Pongsriiam
Department of Mathematics
Faculty of Science
Nakhon Pathom 73000
A positive integer n is a b-adic palindrome if the
representation of n in base b reads the same backward
as forward. Let sb be the reciprocal sum of
all b-adic palindromes. In this article, we obtain upper and
lower bounds, and an asymptotic formula for sb.
We also show that the sequence (sb)b
≥ 2 is strictly increasing and log-concave.
Full version: pdf,
(Concerned with sequences
Received May 27 2019; revised versions received October 7 2019; December 10 2019.
Published in Journal of Integer Sequences,
December 27 2019.
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