A245998 Number of length 3+2 0..n arrays with no pair in any consecutive three terms totalling exactly n.
2, 18, 164, 676, 2262, 5766, 13064, 25992, 48170, 82810, 135852, 212268, 320894, 468846, 668432, 929296, 1267794, 1696482, 2236340, 2903220, 3723302, 4716118, 5913624, 7339416, 9031802, 11018826, 13345724, 16045372, 19170510, 22759230
Offset: 1
Keywords
Examples
Some solutions for n=10 ..6....9....2....7....1...10....9....7....9....9....3....5....1....5....5....6 ..8....9....7...10....4....8....8....9...10....6....9....6....5....6....8....1 ..3...10...10....9....3....4...10....0....3....2....2....1....2....7....3....5 ..6....2....5....4....2....9...10....3....2...10....4....2....1....2....5....1 ..3....2...10....4....9...10....6....0....9....9...10....3....7....1....8....0
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Formula
Empirical: a(n) = 3*a(n-1) -8*a(n-3) +6*a(n-4) +6*a(n-5) -8*a(n-6) +3*a(n-8) -a(n-9).
Empirical: G.f.: 2*x*(1+6*x+55*x^2+100*x^3+183*x^4+86*x^5+49*x^6) / ( (1+x)^3*(x-1)^6 ). - R. J. Mathar, Aug 10 2014
Comments