OFFSET
1,1
COMMENTS
Number of terms in A002779 with exactly n digits.
a(24) = a(30) = a(38) = a(40) = 0. - Robert Price, Apr 26 2019
a(2*k+1) > 0 since (10^k+1)^2 is a palindrome of 2*k+1 digits. - Chai Wah Wu, Jun 14 2024
LINKS
G. J. Simmons, Palindromic powers, J. Rec. Math., 3 (No. 2, 1970), 93-98. [Annotated scanned copy] See page 95.
MATHEMATICA
Table[Length[Select[Range[If[n == 1, 0, Ceiling[Sqrt[10^(n - 1)]]], Floor[Sqrt[10^n]]], #^2 == IntegerReverse[#^2] &]], {n, 15}] (* Robert Price, Apr 26 2019 *)
CROSSREFS
KEYWORD
nonn,base,more
AUTHOR
N. J. A. Sloane, Oct 23 2015
EXTENSIONS
a(13)-a(19) from Chai Wah Wu, Oct 24 2015
a(20) from Robert Price, Apr 26 2019
a(21)-a(44) (using A002778) from Chai Wah Wu, Sep 16 2021
STATUS
approved