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A218035 Number of n-digit palindromes with squares that are also palindromes. 0

%I

%S 4,2,5,3,8,5,13,9,22,16,37,27,60,43,93,65,138,94

%N Number of n-digit palindromes with squares that are also palindromes.

%C Number of n-digit terms in A057135.

%F Conjecture: a(n) = n^3/48 - n^2/8 + 2n/3 + 1 if n even, see A011826.

%F Conjecture: a(n) = n^3/24 - 3n^2/8 + 59n/24 - 1/8 if n odd, n > 1.

%e For n=4, the solutions are:

%e 1001, 1001^2 = 1002001,

%e 1111, 1111^2 = 1234321,

%e 2002, 2002^2 = 4008004.

%Y Cf. A050683, A070252.

%K nonn,base

%O 1,1

%A _David Zvirbulis_, Oct 19 2012

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Last modified December 10 18:10 EST 2019. Contains 329901 sequences. (Running on oeis4.)