cp's OEIS Frontend

A189324 Number of nondecreasing arrangements of n+2 numbers in 0..7 with the last equal to 7 and each after the second equal to the sum of one or two of the preceding four.

%I A189324 #8 May 02 2018 09:22:51
%S A189324 11,17,31,51,91,157,253,374,509,649,789,929,1069,1209,1349,1489,1629,
%T A189324 1769,1909,2049,2189,2329,2469,2609,2749,2889,3029,3169,3309,3449,
%U A189324 3589,3729,3869,4009,4149,4289,4429,4569,4709,4849,4989,5129,5269,5409,5549
%N A189324 Number of nondecreasing arrangements of n+2 numbers in 0..7 with the last equal to 7 and each after the second equal to the sum of one or two of the preceding four.
%C A189324 Column 7 of A189326.
%H A189324 R. H. Hardin, <a href="/A189324/b189324.txt">Table of n, a(n) for n = 1..200</a>
%F A189324 Empirical: a(n) = 140*n - 751 for n>8.
%F A189324 Empirical g.f.: x*(11 - 5*x + 8*x^2 + 6*x^3 + 20*x^4 + 26*x^5 + 30*x^6 + 25*x^7 + 14*x^8 + 5*x^9) / (1 - x)^2. - _Colin Barker_, May 02 2018
%e A189324 Some solutions for n=3:
%e A189324 ..1....7....2....2....1....3....3....1....1....3....1....1....1....4....1....1
%e A189324 ..4....7....5....5....3....4....4....3....3....7....6....3....5....7....2....5
%e A189324 ..5....7....5....5....4....7....4....4....3....7....7....4....6....7....3....6
%e A189324 ..6....7....5....7....7....7....7....5....4....7....7....4....6....7....5....7
%e A189324 ..7....7....7....7....7....7....7....7....7....7....7....7....7....7....7....7
%Y A189324 Cf. A189326.
%K A189324 nonn
%O A189324 1,1
%A A189324 _R. H. Hardin_, Apr 20 2011