A207101 Number of 0..n arrays x(0..3) of 4 elements with each no smaller than the sum of its two previous neighbors modulo (n+1).

8, 26, 68, 140, 274, 462, 760, 1158, 1720, 2431, 3392, 4550, 6048, 7825, 10032, 12597, 15726, 19285, 23540, 28343, 33968, 40250, 47536, 55575, 64792, 74916, 86380, 98890, 112970, 128216, 145248, 163636, 184008, 205905, 230064, 255892, 284240, 314483

Offset: 1

Author

R. H. Hardin, Feb 15 2012

Keywords

• nonn

Comments

Row 4 of A207100.

Examples

			Some solutions for n=5:
..2....3....1....1....3....3....3....1....3....3....4....3....0....4....0....0
..4....3....1....5....3....4....3....1....3....3....5....3....0....4....2....0
..2....4....4....4....3....3....3....5....4....4....3....3....2....2....4....4
..3....1....5....5....1....2....0....4....2....4....5....2....3....3....2....4
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Crossrefs

Cf. A207100.

Formula

Empirical: a(n) = 3*a(n-2) + 2*a(n-3) - 3*a(n-4) - 6*a(n-5) + 6*a(n-7) + 3*a(n-8) - 2*a(n-9) - 3*a(n-10) + a(n-12).

Empirical g.f.: x*(8 + 26*x + 44*x^2 + 46*x^3 + 42*x^4 + 32*x^5 + 18*x^6 + 4*x^7 - 2*x^8 - 3*x^9 + x^11) / ((1 - x)^5*(1 + x)^3*(1 + x + x^2)^2). - Colin Barker, Jun 19 2018