0,1

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

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.

Sequence in context: A046366 A097374 A046361 this_sequence A121054 A031003 A036345

Adjacent sequences: A017566 A017567 A017568 this_sequence A017570 A017571 A017572

nonn,easy

njas