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A263618 Number of palindromic squares with exactly n digits. 8
4, 0, 3, 0, 7, 1, 5, 0, 11, 0, 5, 1, 19, 0, 13, 1, 25, 0, 18, 0 (list; graph; refs; listen; history; text; internal format)
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

LINKS

Table of n, a(n) for n=1..20.

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

Cf. A002778, A002779, A263617, A263617, A263619, A263620.

Sequence in context: A327305 A290328 A200682 * A156788 A130801 A280579

Adjacent sequences:  A263615 A263616 A263617 * A263619 A263620 A263621

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

STATUS

approved

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Last modified August 11 23:04 EDT 2020. Contains 336434 sequences. (Running on oeis4.)