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A006528 a(n) = (n^4 + n^2 + 2*n)/4.
(Formerly M4160)
17
0, 1, 6, 24, 70, 165, 336, 616, 1044, 1665, 2530, 3696, 5226, 7189, 9660, 12720, 16456, 20961, 26334, 32680, 40110, 48741, 58696, 70104, 83100, 97825, 114426, 133056, 153874, 177045, 202740, 231136, 262416, 296769, 334390, 375480, 420246, 468901, 521664, 578760 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
COMMENTS
Number of ways to color vertices of a square using <= n colors, allowing only rotations.
Also product of first and last terms in n-th row of a triangle of form: row(1)= 1; row(2)= 2,3; row(3) = 4, 5, 6, ... . - Dave Durgin, Aug 17 2012
REFERENCES
Nick Baxter, The Burnside di-lemma: combinatorics and puzzle symmetry, in Tribute to a Mathemagician, Peters, 2005, pp. 199-210.
M. Gardner, New Mathematical Diversions from Scientific American. Simon and Schuster, NY, 1966, p. 246.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
Simon Plouffe, Approximations de séries génératrices et quelques conjectures, Dissertation, Université du Québec à Montréal, 1992; arXiv:0911.4975 [math.NT], 2009.
Simon Plouffe, 1031 Generating Functions, Appendix to Thesis, Montreal, 1992.
FORMULA
a(n) = n*(n+1)*(n^2-n+2)/4.
a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5). - Vincenzo Librandi, Apr 30 2012
From Stefano Spezia, Oct 11 2023: (Start)
O.g.f.: x*(1 + x + 4*x^2)/(1 - x)^5.
E.g.f.: exp(x)*x*(4 + 8*x + 6*x^2 + x^3)/4. (End)
MAPLE
A006528:=-z*(1+z+4*z**2)/(z-1)**5; # Simon Plouffe in his 1992 dissertation
a:=n->add(n+add(binomial(n, 2), j=1..n), j=0..n):seq(a(n)/2, n=0..35); # Zerinvary Lajos, Aug 26 2008
MATHEMATICA
Table[CycleIndex[CyclicGroup[4], t]/.Table[t[i]->n, {i, 1, 4}], {n, 0, 20}] (* Geoffrey Critzer, Mar 13 2011*)
Table[(n^4+n^2+2*n)/4, {n, 0, 40}] (* or *) LinearRecurrence[{5, -10, 10, -5, 1}, {0, 1, 6, 24, 70}, 40] (* Harvey P. Dale, Jan 13 2019 *)
PROG
(Magma) I:=[0, 1, 6, 24, 70]; [n le 5 select I[n] else 5*Self(n-1)-10*Self(n-2)+10*Self(n-3)-5*Self(n-4)+Self(n-5): n in [1..40]]; // Vincenzo Librandi, Apr 30 2012
(PARI) a(n) = n*(n+1)*(n^2-n+2)/4; /* Joerg Arndt, Apr 30 2012 */
CROSSREFS
Row n=2 of A343095.
Cf. A002817 (square colorings).
Sequence in context: A369177 A234271 A338512 * A052749 A337021 A262445
KEYWORD
nonn,easy
AUTHOR
STATUS
approved

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Last modified March 28 16:58 EDT 2024. Contains 371254 sequences. (Running on oeis4.)