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A008782
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For any circular arrangement of 0..n-1, let S = sum of squares of every sum of three contiguous numbers; then a(n) = # of distinct values of S.
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2
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1, 1, 1, 1, 8, 17, 55, 110, 184, 272, 384, 522, 681, 874, 1101, 1354
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,5
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MAPLE
| A008782 := proc(n) local S, i, j, sumsq, npermut, p, per ; S := {} ; npermut := combinat[permute]([seq(i, i=0..n-1)]) ; for p from 1 to nops(npermut) do per := op(p, npermut) ; sumsq := 0 ; for i from 0 to n-1 do sumsq := sumsq + (add(op(1+(j mod n), per), j=i..i+2)) ^2 ; od ; S := S union {sumsq} ; od ; RETURN(nops(S)) ; end: for n from 1 to 20 do print(A008782(n)) ; od : - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 18 2007
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CROSSREFS
| Cf. A007773.
Sequence in context: A153873 A111325 A173056 * A146078 A097058 A186255
Adjacent sequences: A008779 A008780 A008781 * A008783 A008784 A008785
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KEYWORD
| nonn,more
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AUTHOR
| Olivier Gerard (olivier.gerard(AT)gmail.com)
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EXTENSIONS
| More terms from Reiner Martin (reinermartin(AT)hotmail.com), May 19 2001
a(11)-a(13) from Sean A. Irvine (sairvin(AT)xtra.co.nz), May 05 2010
a(14)-a(16) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Nov 30 2010
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