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A218035 Number of n-digit palindromes with squares that are also palindromes. 0
4, 2, 5, 3, 8, 5, 13, 9, 22, 16, 37, 27, 60, 43, 93, 65, 138, 94 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Number of n-digit terms in A057135.

LINKS

Table of n, a(n) for n=1..18.

FORMULA

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

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

EXAMPLE

For n=4, the solutions are:

1001, 1001^2 = 1002001,

1111, 1111^2 = 1234321,

2002, 2002^2 = 4008004.

CROSSREFS

Cf. A050683, A070252.

Sequence in context: A185511 A199855 A127914 * A090964 A219159 A213928

Adjacent sequences:  A218032 A218033 A218034 * A218036 A218037 A218038

KEYWORD

nonn,base

AUTHOR

David Zvirbulis, Oct 19 2012

STATUS

approved

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Last modified November 17 16:08 EST 2019. Contains 329241 sequences. (Running on oeis4.)