Original entry on oeis.org
0, 1, 2, 10, 34, 131, 484, 1812, 6756, 25221, 94118, 351262, 1310918, 4892423, 18258760, 68142632, 254311752, 949104393, 3542105802, 13219318834, 49335169514, 184121359243, 687150267436, 2564479710524, 9570768574636, 35718594588045
Offset: 1
A192376
Constant term of the reduction by x^2->x+2 of the polynomial p(n,x) defined below in Comments.
Original entry on oeis.org
1, 0, 7, 16, 73, 256, 975, 3616, 13521, 50432, 188247, 702512, 2621849, 9784832, 36517535, 136285248, 508623521, 1898208768, 7084211623, 26438637648, 98670339049, 368242718464, 1374300534895, 5128959421024, 19141537149297, 71437189176064
Offset: 1
The first five polynomials p(n,x) and their reductions are as follows:
p(0,x)=1 -> 1
p(1,x)=2x -> 2x
p(2,x)=4+x+3x^2 -> 7+4x
p(3,x)=16x+4x^2+4x^3 -> 16+20x
p(4,x)=16+8x+41x^2+10x^3+5x^4 -> 73+68x.
From these, read A192376=(1,0,7,16,73,...) and A192377=(0,2,4,20,68,...).
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q[x_] := x + 2; d = Sqrt[x + 1];
p[n_, x_] := ((x + d)^n - (x - d)^ n )/(2 d) (* Cf. A162517 *)
Table[Expand[p[n, x]], {n, 1, 6}]
reductionRules = {x^y_?EvenQ -> q[x]^(y/2), x^y_?OddQ -> x q[x]^((y - 1)/2)};
t = Table[Last[Most[FixedPointList[Expand[#1 /. reductionRules] &, p[n, x]]]], {n, 1, 30}]
Table[Coefficient[Part[t, n], x, 0], {n, 1, 30}] (* A192376 *)
Table[Coefficient[Part[t, n], x, 1], {n, 1, 30}] (* A192377 *)
Table[Coefficient[Part[t, n]/2, x, 1], {n, 1, 30}] (* A192378 *)
Showing 1-2 of 2 results.
Comments