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 A056514 Number of primitive (period n) periodic palindromic structures using a maximum of three different symbols. 5
 1, 1, 1, 1, 3, 4, 9, 13, 28, 39, 84, 121, 244, 364, 741, 1088, 2200, 3280, 6591, 9841, 19720, 29510, 59169, 88573, 177240, 265716, 531804, 797121, 1594684, 2391484, 4783968, 7174453, 14350000, 21523238, 43050000, 64570064, 129143196, 193710244, 387430329, 581130368, 1162271280 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 COMMENTS For example, aaabbb is not a (finite) palindrome but it is a periodic palindrome. Permuting the symbols will not change the structure. REFERENCES M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia. [See A056391 for pdf file of Chap. 2] LINKS Andrew Howroyd, Table of n, a(n) for n = 0..200 FORMULA a(n) = Sum_{d|n} mu(d)*A056504(n/d) for n > 0. Moebius transform of A056504. a(n) = Sum_{k=1..3} A285037(n, k) for n > 0. - Andrew Howroyd, Apr 08 2017 CROSSREFS Cf. A056477, A056504, A285037. Sequence in context: A000624 A244703 A232801 * A151517 A219043 A050163 Adjacent sequences:  A056511 A056512 A056513 * A056515 A056516 A056517 KEYWORD nonn AUTHOR EXTENSIONS Corrected by Franklin T. Adams-Watters and T. D. Noe, Oct 25 2006 a(17)-a(35) from Andrew Howroyd, Apr 08 2017 a(0)=1 prepended and terms a(36) and beyond from Andrew Howroyd, Oct 01 2019 STATUS approved

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Last modified February 20 18:30 EST 2020. Contains 332082 sequences. (Running on oeis4.)