A106586 - OEIS

A106586

Digit next to last in squares ending in 6.

1, 3, 9, 5, 7, 7, 5, 9, 3, 1, 1, 3, 9, 5, 7, 7, 5, 9, 3, 1, 1, 3, 9, 5, 7, 7, 5, 9, 3, 1, 1, 3, 9, 5, 7, 7, 5, 9, 3, 1, 1, 3, 9, 5, 7, 7, 5, 9, 3, 1, 1, 3, 9, 5, 7, 7, 5, 9, 3, 1, 1, 3, 9, 5, 7, 7, 5, 9, 3, 1, 1, 3, 9, 5, 7, 7, 5, 9, 3, 1, 1, 3, 9, 5, 7, 7, 5, 9, 3, 1, 1, 3, 9, 5, 7, 7, 5, 9, 3, 1, 1, 3, 9, 5, 7

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OFFSET

1,2

COMMENTS

Entries are always one of the odd digits 1,3,5,7,9.

Palindrome of period 10. [From Paul Curtz, Jan 04 2009]

LINKS

Table of n, a(n) for n=1..105.

Index entries for linear recurrences with constant coefficients, signature (1,-1,1,-1,1,-1,1,-1,1).

FORMULA

G.f. -x*(1 +2*x +7*x^2 -2*x^3 +9*x^4 -2*x^5 +7*x^6 +2*x^7 +x^8) / ( (x-1) *(1+x+x^2+x^3+x^4) *(1-x+x^2-x^3+x^4) ). - R. J. Mathar, Jul 28 2013

MATHEMATICA