cp's OEIS Frontend

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.

A299499 Triangle read by rows, T(n,k) = [x^k] Sum_{k=0..n} p_{n,k}(x) where p_{n,k}(x) = x^k*binomial(n, k)*hypergeom([-k, k-n, k-n], [1, -n], 1/x), for 0 <= k <= n.

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%I A299499 #19 Feb 26 2018 04:19:45
%S A299499 1,1,1,2,2,1,5,5,3,1,11,16,9,4,1,26,44,34,14,5,1,63,122,111,60,20,6,1,
%T A299499 153,341,351,225,95,27,7,1,376,940,1103,796,400,140,35,8,1,931,2581,
%U A299499 3384,2764,1561,651,196,44,9,1,2317,7064,10224,9304,5915,2772,994,264,54,10,1
%N A299499 Triangle read by rows, T(n,k) = [x^k] Sum_{k=0..n} p_{n,k}(x) where p_{n,k}(x) = x^k*binomial(n, k)*hypergeom([-k, k-n, k-n], [1, -n], 1/x), for 0 <= k <= n.
%F A299499 Let P_{n}(x) = Sum_{k=0..n} p_{n,k}(x) then
%F A299499 2^n*P_{n}(1/2) = A298611(n).
%F A299499 P_{n}(-1) = A182883(n), P_{n}(0) = A051286(n).
%F A299499 P_{n}( 1) = A108626(n), P_{n}(2) = A299443(n).
%F A299499 The general case: for fixed k the sequence P_{n}(k) with n >= 0 has the generating function ogf(k, x) = (1-2*(k+1)*x + (k^2+2*k-1)*x^2 + 2*(k-1)*x^3 + x^4)^(-1/2).  The example section shows the start of this square array of sequences.
%F A299499 These sequences can be computed by the recurrence P(n,k) = ((2-n)*P(n-4,k)+(3-2*n)*(k-1)*P(n-3,k)+(k^2+2*k-1)*(1-n)*P(n-2,k)+(2*n-1)*(k+1)*P(n-1,k))/n with initial values 1, k+1, (k+1)^2+1 and (k+1)^3+2*k+4.
%F A299499 The partial polynomials p_{n,k}(x) reduce for x = 1 to A108625 (seen as a triangle).
%e A299499 The partial polynomials p_{n,k}(x) start:
%e A299499 [0] 1
%e A299499 [1] 1, x
%e A299499 [2] 1, 2*x+ 1,    x^2
%e A299499 [3] 1, 3*x+ 4,  3*x^2+ 2*x,      x^3
%e A299499 [4] 1, 4*x+ 9,  6*x^2+12*x+1,  4*x^3+ 3*x^2,       x^4
%e A299499 [5] 1, 5*x+16, 10*x^2+36*x+9, 10*x^3+24*x^2+3*x, 5*x^4+4*x^3, x^5
%e A299499 .
%e A299499 The polynomials P_{n}(x) start:
%e A299499 [0]   1
%e A299499 [1]   1 +    x
%e A299499 [2]   2 +  2*x +    x^2
%e A299499 [3]   5 +  5*x +  3*x^2 +    x^3
%e A299499 [4]  11 + 16*x +  9*x^2 +  4*x^3 +   x^4
%e A299499 [5]  26 + 44*x + 34*x^2 + 14*x^3 + 5*x^4 + x^5
%e A299499 .
%e A299499 The triangle starts:
%e A299499 [0]   1
%e A299499 [1]   1,    1
%e A299499 [2]   2,    2,    1
%e A299499 [3]   5,    5,    3,    1
%e A299499 [4]  11,   16,    9,    4,    1
%e A299499 [5]  26,   44,   34,   14,    5,   1
%e A299499 [6]  63,  122,  111,   60,   20,   6,   1
%e A299499 [7] 153,  341,  351,  225,   95,  27,   7,  1
%e A299499 [8] 376,  940, 1103,  796,  400, 140,  35,  8, 1
%e A299499 [9] 931, 2581, 3384, 2764, 1561, 651, 196, 44, 9, 1
%e A299499 .
%e A299499 The square array P_{n}(k) near k=0:
%e A299499 ......  [k=-2] 1, -1,  2, -1,  -1,   10,  -25,    51,    -68,     41, ...
%e A299499 A182883 [k=-1] 1,  0,  1,  2,   1,    6,    7,    12,     31,     40, ...
%e A299499 A051286 [k=0]  1,  1,  2,  5,  11,   26,   63,   153,    376,    931, ...
%e A299499 A108626 [k=1]  1,  2,  5, 14,  41,  124,  383,  1200,   3799,  12122, ...
%e A299499 A299443 [k=2]  1,  3, 10, 35, 127,  474, 1807,  6999,  27436, 108541, ...
%e A299499 ......  [k=3]  1,  4, 17, 74, 329, 1490, 6855, 31956, 150607, 716236, ...
%p A299499 CoeffList := p -> op(PolynomialTools:-CoefficientList(p,x)):
%p A299499 PrintPoly := p -> print(sort(expand(p),x,ascending)):
%p A299499 T := (n,k) -> x^k*binomial(n, k)*hypergeom([-k,k-n,k-n], [1,-n], 1/x):
%p A299499 P := [seq(add(simplify(T(n,k)),k=0..n), n=0..10)]:
%p A299499 seq(CoeffList(p), p in P); seq(PrintPoly(p), p in P);
%p A299499 R := proc(n,k) option remember; # Recurrence
%p A299499 if n < 4 then return [1,k+1,(k+1)^2+1,(k+1)^3+2*k+4][n+1] fi; ((2-n)*R(n-4,k)+
%p A299499 (3-2*n)*(k-1)*R(n-3,k)+(k^2+2*k-1)*(1-n)*R(n-2,k)+(2*n-1)*(k+1)*R(n-1,k))/n end:
%p A299499 for k from -2 to 3 do lprint(seq(R(n,k), n=0..9)) od;
%t A299499 nmax = 10;
%t A299499 p[n_, k_, x_] := x^k*Binomial[n, k]*HypergeometricPFQ[{-k, k-n, k-n}, {1, -n}, 1/x];
%t A299499 p[n_, x_] := Sum[p[n, k, x], {k, 0, n}];
%t A299499 Table[CoefficientList[p[n, x], x], {n, 0, nmax}] // Flatten (* _Jean-François Alcover_, Feb 26 2018 *)
%Y A299499 Cf. A051286, A108625, A108626, A182883, A298611, A299443, A299500.
%K A299499 nonn,tabl
%O A299499 0,4
%A A299499 _Peter Luschny_, Feb 11 2018