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A285042

Number of primitive (period n) periodic palindromic structures of length n using an infinite alphabet.

1, 1, 1, 1, 3, 4, 10, 14, 36, 50, 138, 202, 562, 876, 2589, 4134, 12828, 21146, 69115, 115974, 398619, 678554, 2450202, 4213596, 15939338, 27644432, 109304036, 190899270, 787013630, 1382958544, 5931819804, 10480142146, 46673246440, 82864869600, 382473261356

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OFFSET

0,5

COMMENTS

See A285037 for additional information. Permuting the symbols will not change the structure.

LINKS

Andrew Howroyd, Table of n, a(n) for n = 0..500

FORMULA

a(n) = Sum_{d | n} mu(n/d) * A285013(d) for n > 0.

PROG

(PARI) \\ Requires T from A285037.

seq(n)={my(A=T(n)); concat([1], vector(n, i, vecsum(A[i, ])))} \\ Andrew Howroyd, Oct 02 2019