This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A245997 #8 Jul 23 2025 11:30:55 %S A245997 2,12,68,208,534,1116,2120,3648,5930,9100,13452,19152,26558,35868, %T A245997 47504,61696,78930,99468,123860,152400,185702,224092,268248,318528, %U A245997 375674,440076,512540,593488,683790,783900,894752,1016832,1151138,1298188 %N A245997 Number of length 2+2 0..n arrays with no pair in any consecutive three terms totalling exactly n. %C A245997 Row 2 of A245995 %H A245997 R. H. Hardin, <a href="/A245997/b245997.txt">Table of n, a(n) for n = 1..210</a> %F A245997 Empirical: a(n) = 3*a(n-1) -a(n-2) -5*a(n-3) +5*a(n-4) +a(n-5) -3*a(n-6) +a(n-7). %F A245997 Empirical: G.f.: -2*x*(1+3*x+17*x^2+13*x^3+14*x^4) / ( (1+x)^2*(x-1)^5 ). - _R. J. Mathar_, Aug 10 2014 %e A245997 Some solutions for n=10 %e A245997 ..5....2....2....2....8....9....2....4....6....8....8....5....3....0....1....6 %e A245997 ..0....2....7....7....7....4....9...10....7....6...10....0....6....4....2...10 %e A245997 ..1....1...10....2....5....3....6....4....2....6....7....7....0....4....6....9 %e A245997 ..8....1....5....7....0....3....9....5....6....3...10....7....0...10....2....3 %K A245997 nonn %O A245997 1,1 %A A245997 _R. H. Hardin_, Aug 09 2014