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A030676 Smallest nontrivial extension of n-th palindrome which is a square. 2
16, 25, 36, 49, 529, 64, 729, 81, 900, 1156, 225, 3364, 441, 55225, 66049, 7744, 8836, 99225, 101124, 111556, 12100, 131044, 14161, 15129, 16129, 17161, 181476, 191844, 2025, 212521, 22201, 232324, 242064, 25281, 26244, 27225 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

MAPLE

revdigs:= proc(n)

local L, nL, i;

L:= convert(n, base, 10);

add(L[-i]*10^(i-1), i=1..nops(L));

end:

g:= proc(d) local m, x, y;

  if d::even then

    m:= d/2;

    seq(x*10^m+revdigs(x), x=10^(m-1)..10^m-1)

  else

    m:= (d-1)/2;

    seq(seq(x*10^(m+1)+y*10^m+revdigs(x), y=0..9), x=10^(m-1)..10^m-1)

  fi

end proc:

g(1):= $1..9:

f:= proc(x) local d, y;

  for d from 1 do

    y:= ceil(sqrt(x*10^d))^2;

    if y < (x+1)*10^d then return y fi

  od;

end proc:

map(f, [g(1), g(2), g(3)]); # Robert Israel, Aug 12 2018

CROSSREFS

Cf. A030677.

Sequence in context: A291334 A175689 A030666 * A264604 A218439 A192689

Adjacent sequences:  A030673 A030674 A030675 * A030677 A030678 A030679

KEYWORD

nonn,base,look

AUTHOR

Patrick De Geest

STATUS

approved

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Last modified May 9 18:53 EDT 2021. Contains 343744 sequences. (Running on oeis4.)