The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A227555 Number of n X 3 0,1 arrays indicating 2 X 2 subblocks of some larger (n+1) X 4 binary array having nonzero determinant, with rows and columns of the latter in lexicographically nondecreasing order. 1
 7, 33, 147, 585, 2080, 6653, 19356, 51827, 129090, 301882, 668004, 1407882, 2841813, 5519404, 10355651, 18833130, 33296081, 57369975, 96549697, 159011007, 256713726, 406881423, 633961558, 972192389, 1468928820, 2188909112 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = (1/2217600)*n^11 - (1/201600)*n^10 + (1/3780)*n^9 - (9/4480)*n^8 + (6403/201600)*n^7 - (4609/28800)*n^6 + (4331/4032)*n^5 - (40753/13440)*n^4 + (1339067/151200)*n^3 - (443809/50400)*n^2 + (83507/9240)*n. Conjectures from Colin Barker, Sep 08 2018: (Start) G.f.: x*(7 - 51*x + 213*x^2 - 541*x^3 + 967*x^4 - 1246*x^5 + 1197*x^6 - 848*x^7 + 439*x^8 - 150*x^9 + 31*x^10) / (1 - x)^12. a(n) = 12*a(n-1) - 66*a(n-2) + 220*a(n-3) - 495*a(n-4) + 792*a(n-5) - 924*a(n-6) + 792*a(n-7) - 495*a(n-8) + 220*a(n-9) - 66*a(n-10) + 12*a(n-11) - a(n-12) for n>12. (End) EXAMPLE Some solutions for n=4: ..0..0..1....0..1..0....0..1..0....0..1..0....0..1..0....0..1..0....0..0..1 ..0..0..0....0..0..0....0..0..0....1..0..0....0..0..0....0..0..0....0..0..0 ..0..0..0....0..1..1....0..0..0....0..0..1....0..1..1....1..0..0....0..0..0 ..0..0..0....0..0..1....0..1..1....1..1..0....1..0..1....0..1..1....1..0..1 CROSSREFS Column 3 of A227558. Sequence in context: A225895 A089106 A211829 * A304278 A155603 A282991 Adjacent sequences: A227552 A227553 A227554 * A227556 A227557 A227558 KEYWORD nonn AUTHOR R. H. Hardin, Jul 16 2013 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified September 19 09:46 EDT 2024. Contains 376008 sequences. (Running on oeis4.)