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4, 16, 28, 40, 52, 64, 76, 88, 100, 112, 124, 136, 148, 160, 172, 184, 196, 208, 220, 232, 244, 256, 268, 280, 292, 304, 316, 328, 340, 352, 364, 376, 388, 400, 412, 424, 436, 448, 460, 472, 484, 496, 508, 520, 532, 544, 556, 568, 580, 592, 604, 616, 628
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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COMMENTS
| Apart from initial term(s), dimension of the space of weight 2n cusp forms for Gamma_0( 46 ).
Number of 6 X n 0-1 matrices avoiding simultaneously the right angled numbered polyomino patterns (ranpp) (00;1), (01;0), (11;0) and (01;1). An occurrence of a ranpp (xy;z) in a matrix A=(a(i,j)) is a triple (a(i1,j1), a(i1,j2), a(i2,j1)) where i1<i2, j1<j2 and these elements are in the same relative order as those in the triple (x,y,z). In general, the number of m x n 0-1 matrices in question is given by 2^m+2m(n-1). Cf. m=2: A008574; m=3: A016933; m=4: A022144; m=5: A017293; . - Sergey Kitaev (kitaev(AT)ms.uky.edu), Nov 13 2004
Except for 4, exponents e such that x^e-x^2+1 is reducible.
If Y and Z are 2-blocks of a (3n+1)-set X then a(n-1) is the number of 3-subsets of X intersecting both Y and Z. - Milan R. Janjic (agnus(AT)blic.net), Oct 28 2007
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 0..5000
Milan Janjic, Two Enumerative Functions
Tanya Khovanova, Recursive Sequences
William A. Stein, Dimensions of the spaces S_k(Gamma_0(N))
William A. Stein, The modular forms database
S. Kitaev, On multi-avoidance of right angled numbered polyomino patterns, Integers: Electronic Journal of Combinatorial Number Theory 4 (2004), A21, 20pp.
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MATHEMATICA
| 12*Range[0, 200]+4 (*From Vladimir Joseph Stephan Orlovsky, Feb 19 2011*)
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PROG
| (MAGMA) [12*n+4: n in [0..50]]; // Vincenzo Librandi, May 04 2011
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CROSSREFS
| Cf. A008594, A017533, A017545.
Sequence in context: A046366 A097374 A046361 * A161335 A121054 A160410
Adjacent sequences: A017566 A017567 A017568 * A017570 A017571 A017572
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KEYWORD
| nonn,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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