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.

Showing 1-5 of 5 results.

A002203 Companion Pell numbers: a(n) = 2*a(n-1) + a(n-2), a(0) = a(1) = 2.

Original entry on oeis.org

2, 2, 6, 14, 34, 82, 198, 478, 1154, 2786, 6726, 16238, 39202, 94642, 228486, 551614, 1331714, 3215042, 7761798, 18738638, 45239074, 109216786, 263672646, 636562078, 1536796802, 3710155682, 8957108166, 21624372014, 52205852194, 126036076402, 304278004998
Offset: 0

Views

Author

N. J. A. Sloane

Keywords

Comments

Also the number of matchings (independent edge sets) of the n-sunlet graph. - Eric W. Weisstein, Mar 09 2016
Apart from first term, same as A099425. - Peter Shor, May 12 2005
The signed sequence 2, -2, 6, -14, 34, -82, 198, -478, 1154, -2786, ... is the Lucas V(-2,-1) sequence. - R. J. Mathar, Jan 08 2013
Also named "Pell-Lucas numbers", apparently by Hoggatt and Alexanderson (1976), after the English mathematician John Pell (1611-1685) and the French mathematician Édouard Lucas (1842-1891). - Amiram Eldar, Oct 02 2023

References

  • Paul Bachmann, Niedere Zahlentheorie (1902, 1910), reprinted Chelsea, NY, 1968, vol. 2, p. 76.
  • M. R. Bacon and C. K. Cook, Some properties of Oresme numbers and convolutions ..., Fib. Q., 62:3 (2024), 233-240.
  • Paulo Ribenboim, The Book of Prime Number Records. Springer-Verlag, NY, 2nd ed., 1989, p. 43.
  • Paulo Ribenboim, My Numbers, My Friends: Popular Lectures on Number Theory, Springer-Verlag, NY, 2000, p. 3.
  • Paulo Ribenboim, The Little Book of Bigger Primes, Springer-Verlag NY 2004. See pp. 46, 61.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

Crossrefs

Cf. A001333 (half), A302946 (squared).
Cf. A000129, A100227, A244854, A002315.
Bisections are A003499 and A077444.

Programs

  • Haskell
    a002203 n = a002203_list !! n
a002203_list =
   2 : 2 : zipWith (+) (map (* 2) $ tail a002203_list) a002203_list
-- Reinhard Zumkeller, Oct 03 2011
  • Magma
    I:=[2,2]; [n le 2 select I[n] else 2*Self(n-1)+Self(n-2): n in [1..35]]; // Vincenzo Librandi, Aug 15 2015
  • Maple
    A002203 := proc(n)
    option remember;
    if n <= 1 then
        2;
    else
        2*procname(n-1)+procname(n-2) ;
    end if;
end proc: # R. J. Mathar, May 11 2013
# second Maple program:
a:= n-> (<<0|1>, <1|2>>^n. <<2, 2>>)[1, 1]:
seq(a(n), n=0..30);  # Alois P. Heinz, Jan 26 2018
a := n -> 2*I^n*ChebyshevT(n, -I):
seq(simplify(a(n)), n = 0..30);  # Peter Luschny, Dec 03 2023
  • Mathematica
    Table[LucasL[n, 2], {n, 0, 30}] (* Zerinvary Lajos, Jul 09 2009 *)
LinearRecurrence[{2, 1}, {2, 2}, 50] (* Vincenzo Librandi, Aug 15 2015 *)
Table[(1 - Sqrt[2])^n + (1 + Sqrt[2])^n, {n, 0, 20}] // Expand (* Eric W. Weisstein, Oct 03 2017 *)
LucasL[Range[0, 20], 2] (* Eric W. Weisstein, Oct 03 2017 *)
CoefficientList[Series[(2 (1 - x))/(1 - 2 x - x^2), {x, 0, 20}], x] (* Eric W. Weisstein, Oct 03 2017 *)
  • PARI
    first(m)=my(v=vector(m));v[1]=2;v[2]=2;for(i=3,m,v[i]=2*v[i-1]+v[i-2]);v; \\ Anders Hellström, Aug 15 2015
  • PARI
    a(n) = my(w=quadgen(8)); (1+w)^n + (1-w)^n; \\ Michel Marcus, Jun 17 2021
  • Sage
    [lucas_number2(n,2,-1) for n in range(0, 29)] # Zerinvary Lajos, Apr 30 2009

Formula

a(n) = 2 * A001333(n).
a(n) = A100227(n) + 1.
O.g.f.: (2 - 2*x)/(1 - 2*x - x^2). - Simon Plouffe in his 1992 dissertation
a(n) = (1 + sqrt(2))^n + (1 - sqrt(2))^n. - Mario Catalani (mario.catalani(AT)unito.it), Mar 17 2003
a(n) = A000129(2*n)/A000129(n), n > 0. - Paul Barry, Feb 06 2004
From Miklos Kristof, Mar 19 2007: (Start)
Given F(n) = A000129(n), the Pell numbers, and L(n) = a(n), then:
L(n+m) + (-1)^m*L(n-m) = L(n)*L(m).
L(n+m) - (-1)^m*L(n-m) = 8*F(n)*F(m).
L(n+m+k) + (-1)^k*L(n+m-k) + (-1)^m*(L(n-m+k) + (-1)^k*L(n-m-k)) = L(n)*L(m)*L(k).
L(n+m+k) - (-1)^k*L(n+m-k) + (-1)^m*(L(n-m+k) - (-1)^k*L(n-m-k)) = 8*F(n)*L(m)*F(k).
L(n+m+k) + (-1)^k*L(n+m-k) - (-1)^m*(L(n-m+k) + (-1)^k*L(n-m-k)) = 8*F(n)*F(m)*L(k).
L(n+m+k) - (-1)^k*L(n+m-k) - (-1)^m*(L(n-m+k) - (-1)^k*L(n-m-k)) = 8*L(n)*F(m)*F(k).
(End)
a(n) = 2*(A000129(n+1) - A000129(n)). - R. J. Mathar, Nov 16 2007
G.f.: G(0), where G(k) = 1 + 1/(1 - x*(2*k - 1)/(x*(2*k + 1) - 1/G(k + 1))); (continued fraction). - Sergei N. Gladkovskii, Jun 19 2013
a(n) = [x^n] ( (1 + 2*x + sqrt(1 + 4*x + 8*x^2))/2 )^n for n >= 1. - Peter Bala, Jun 23 2015
From Kai Wang, Jan 14 2020: (Start)
A000129(m - n) = (-1)^n * (A000129(m) * a(n) - a(m) * A000129(n))/2.
A000129(m + n) = (A000129(m) * a(n) + a(m)*A000129(n))/2.
a(n)^2 - a(n + 1) * a(n - 1) = (-1)^(n) * 8.
a(n)^2 - a(n + r) * a(n - r) = (-1)^(n - r - 1) * 8 * A000129(r)^2.
a(m) * a(n + 1) - a(m + 1) * a(n) = (-1)^(n - 1) * 8 * A000129(m - n).
a(m - n) = (-1)^(n) * (a(m) * a(n) - 8 * A000129(m) * A000129(n))/2.
a(m + n) = (a(m) * a(n) + 8 * A000129(m) * A000129(n))/2.
(End)
E.g.f.: 2*exp(x)*cosh(sqrt(2)*x). - Stefano Spezia, Jan 15 2020
a(n) = A000129(n+1) + A000129(n-1) for n>0 with a(0)=2. - Rigoberto Florez, Jul 12 2020
a(n) = (-1)^n * (a(n)^3 - a(3*n))/3. - Greg Dresden, Jun 16 2021
a(n) = (a(n+2) + a(n-2))/6 for n >= 2. - Greg Dresden, Jun 23 2021
From Greg Dresden and Tongjia Rao, Sep 09 2021: (Start)
a(3n+2)/a(3n-1) = [14, ..., 14, -3] with (n+1) 14's.
a(3n+3)/a( 3n ) = [14, ..., 14, 7] with n 14's.
a(3n+4)/a(3n+1) = [14, ..., 14, 17] with n 14's. (End)
From Peter Bala, Nov 16 2022: (Start)
a(n) = trace([2, 1; 1, 0]^n) for n >= 1.
The Gauss congruences hold: a(n*p^k) == a(n*p^(k-1)) (mod p^k) for all positive integers n and k and all primes p.
a(3^n) == A271222(n) (mod 3^n). (End)
Sum_{n>=1} arctan(2/a(n))*arctan(2/a(n+1)) = Pi^2/32 (A244854) (Ohtsuka, 2019). - Amiram Eldar, Feb 11 2024
From Peter Bala, Jul 09 2025: (Start)
The following series telescope (Cf. A000032):
For k >= 1, Sum_{n >= 1} (-1)^((k+1)*(n+1)) * a(2*n*k)/(a((2*n-1)*k)*a((2*n+1)*k)) = 1/a(k)^2.
For positive even k, Sum_{n >= 1} 1/(a(k*n) - (a(k) + 2)/a(k*n)) = 1/(a(k) - 2) and
Sum_{n >= 1} (-1)^(n+1)/(a(k*n) + (a(k) - 2)/a(k*n)) = 1/(a(k) + 2).
For positive odd k, Sum_{n >= 1} 1/(a(k*n) - (-1)^n*(a(2*k) + 2)/a(k*n)) = (a(k) + 2)/(2*(a(2*k) - 2)) and
Sum_{n >= 1} (-1)^(n+1)/(a(k*n) - (-1)^n*(a(2*k) + 2)/a(k*n)) = (a(k) - 2)/(2*(a(2*k) - 2)). (End)

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), Dec 03 2001

A102413 Triangle read by rows: T(n,k) is the number of k-matchings in the n-sunlet graph (0 <= k <= n).

Original entry on oeis.org

1, 1, 1, 1, 4, 1, 1, 6, 6, 1, 1, 8, 16, 8, 1, 1, 10, 30, 30, 10, 1, 1, 12, 48, 76, 48, 12, 1, 1, 14, 70, 154, 154, 70, 14, 1, 1, 16, 96, 272, 384, 272, 96, 16, 1, 1, 18, 126, 438, 810, 810, 438, 126, 18, 1, 1, 20, 160, 660, 1520, 2004, 1520, 660, 160, 20, 1, 1, 22, 198, 946, 2618, 4334, 4334, 2618, 946, 198, 22, 1
Offset: 0

Views

Author

Emeric Deutsch, Jan 07 2005

Keywords

Comments

The n-sunlet graph is the corona C'(n) of the cycle graph C(n) and the complete graph K(1); in other words, C'(n) is the graph constructed from C(n) to which for each vertex v a new vertex v' and the edge vv' is added.
Row n contains n+1 terms. Row sums yield A099425. T(n,k) = T(n,n-k).
For n > 2: same recurrence as A008288 and A128966. - Reinhard Zumkeller, Apr 15 2014

Examples

			T(3,2) = 6 because in the graph with vertex set {A,B,C,a,b,c} and edge set {AB,AC,BC,Aa,Bb,Cc} we have the following six 2-matchings: {Aa,BC}, {Bb,AC}, {Cc,AB}, {Aa,Bb}, {Aa,Cc} and {Bb,Cc}.
The triangle starts:
  1;
  1, 1;
  1, 4,  1;
  1, 6,  6, 1;
  1, 8, 16, 8, 1;
From _Eric W. Weisstein_, Apr 03 2018: (Start)
Rows as polynomials:
  1
  1 +    x,
  1 +  4*x +    x^2,
  1 +  6*x +  6*x^2 +    x^3,
  1 +  8*x + 16*x^2 +  8*x^3 +    x^4,
  1 + 10*x + 30*x^2 + 30*x^3 + 10*x^4 + x^5,
  ... (End)

References

  • J. L. Gross and J. Yellen, Handbook of Graph Theory, CRC Press, Boca Raton, 2004, p. 894.
  • F. Harary, Graph Theory, Addison-Wesley, Reading, Mass., 1969, p. 167.

Links

Crossrefs

Cf. A002203 or A099425 (row sums), A006318, A008288.
Cf. A241023 (central terms).

Programs

  • Haskell
    a102413 n k = a102413_tabl !! n !! k
a102413_row n = a102413_tabl !! n
a102413_tabl = [1] : [1,1] : f [2] [1,1] where
   f us vs = ws : f vs ws where
             ws = zipWith3 (((+) .) . (+))
                  ([0] ++ us ++ [0]) ([0] ++ vs) (vs ++ [0])
-- Reinhard Zumkeller, Apr 15 2014
  • Maple
    G:=(1+t*z^2)/(1-(1+t)*z-t*z^2): Gser:=simplify(series(G,z=0,38)): P[0]:=1: for n from 1 to 11 do P[n]:=coeff(Gser,z^n) od:for n from 0 to 11 do seq(coeff(t*P[n],t^k),k=1..n+1) od; # yields sequence in triangular form
  • Mathematica
    CoefficientList[Table[2^-n ((1 + x - Sqrt[1 + x (6 + x)])^n + (1 + x + Sqrt[1 + x (6 + x)])^n), {n, 10}], x] // Flatten (* Eric W. Weisstein, Apr 03 2018 *)
LinearRecurrence[{1 + x, x}, {1, 1 + x, 1 + 4 x + x^2}, 10] // Flatten (* Eric W. Weisstein, Apr 03 2018 *)
Join[{1}, CoefficientList[CoefficientList[Series[(-1 - x - 2 x z)/(-1 + z + x z + x z^2), {z, 0, 10}], z], x]] // Flatten (* Eric W. Weisstein, Apr 03 2018 *)

Formula

G.f.: G(t,z) = (1 + t*z^2) / (1 - (1+t)*z - t*z^2).
For n > 2: T(n,k) = T(n-1,k-1) + T(n-1,k) + T(n-2,k-1), 0 < k < n. - Reinhard Zumkeller, Apr 15 2014 (corrected by Andrew Woods, Dec 08 2014)
From Peter Bala, Jun 25 2015: (Start)
The n-th row polynomial R(n, t) = [z^n] F(z, t)^n, where F(z, t) = 1/2*( 1 + (1 + t)*z + sqrt(1 + 2*(1 + t)*z + (1 + 6*t + t^2)*z^2) ).
exp( Sum_{n >= 1} R(n, t)*z^n/n ) = 1 + (1 + t)*z + (1 + 3*t + t^2)*z^2 + (1 + 5*t + 5*t^2 + t^3)*z^3 + ... is the o.g.f for A008288 read as a triangular array. (End)
From Peter Bala, Aug 01 2024: (Start)
T(n, k) = A008288(n-k, k) + A008288(n-k-1, k-1) (Bihan et al., Proposition 6.6).
T(n, k) = 1 if n = 0 or k = n, else for 1 <= k <= n-1, T(n, k) = Sum_{j = 0..min(n-k, k)} (2^j)*(binomial(n-k, j)*binomial(k, j) + binomial(n-k-1, j)*binomial(k-1, j)).
Let S(x) = (1 - x - (1 - 6*x + x^2)^(1/2))/(2*x) denote the g.f. of the sequence of large Schröder numbers A006318. The signed n-th row polynomial R(n, -x) = 1/S(x)^n + (x*S(x))^n. (End)

Extensions

Row 0 in polynomials and Mathematica programs added by Georg Fischer, Apr 01 2019

A104509 Matrix inverse of triangle A104505, which is the right-hand side of triangle A084610 of coefficients in (1 + x - x^2)^n.

Original entry on oeis.org

1, 1, -1, 3, -2, 1, 4, -6, 3, -1, 7, -12, 10, -4, 1, 11, -25, 25, -15, 5, -1, 18, -48, 60, -44, 21, -6, 1, 29, -91, 133, -119, 70, -28, 7, -1, 47, -168, 284, -296, 210, -104, 36, -8, 1, 76, -306, 585, -699, 576, -342, 147, -45, 9, -1, 123, -550, 1175, -1580, 1485, -1022, 525, -200, 55, -10, 1, 199, -979, 2310, -3454, 3641
Offset: 0

Views

Author

Paul D. Hanna, Mar 11 2005

Keywords

Comments

Riordan array ( (1 + x^2)/(1 - x - x^2), -x/(1 - x - x^2) ) belonging to the hitting time subgroup of the Riordan group (see Peart and Woan). - Peter Bala, Jun 29 2015
The sums of absolute values along steep diagonals in this triangle are: 1, 1, 3, 4 + |-1|, 7 + |-2|, 11 + |-6|, 18 + |-12| + 1, ... and these are the tribonacci numbers A000213 that begin with 1, 1, 1, 3. To see this, replace the y in the g.f. A(x,y) = (1 + x^2)/(1-x-x^2 + x*y) with y=-x^2, multiply by x, and add 1, to obtain the g.f. (1 - x^2)/(1-x-x^2-x^3) for A000213. - Noah Carey and Greg Dresden, Nov 02 2021

Examples

			Rows begin:
   1;
   1,   -1;
   3,   -2,   1;
   4,   -6,   3,   -1;
   7,  -12,  10,   -4,   1;
  11,  -25,  25,  -15,   5,   -1;
  18,  -48,  60,  -44,  21,   -6,   1;
  29,  -91, 133, -119,  70,  -28,   7,  -1;
  47, -168, 284, -296, 210, -104,  36,  -8, 1;
  76, -306, 585, -699, 576, -342, 147, -45, 9, -1; ...

Links

Crossrefs

Leftmost column is A000204 (Lucas numbers). Other columns include: A045925, A067988. Row sums are: {1,0,2,0,2,0,2,...}. Absolute row sums form: A099425. Antidiagonal sums are: {1,1,2,2,2,2,2,...}. Absolute antidiagonal sums are: A084214.
Cf. A104505, A084610, A000213.

Programs

  • Maple
    S:= series((1 + x^2)/(1-x-x^2 + x*y),x, 20):
for n from 0 to 19 do R[n]:= coeff(S,x,n) od:
seq(seq(coeff(R[n],y,j),j=0..n), n=0..19); # Robert Israel, Jun 30 2015
  • Mathematica
    nmax = 11;
T[n_, k_] := Coefficient[(1 + x - x^2)^n, x, n + k];
M = Table[T[n, k], {n, 0, nmax}, {k, 0, nmax}] // Inverse;
Table[M[[n+1, k+1]], {n, 0, nmax}, {k, 0, n}] // Flatten (* Jean-François Alcover, Mar 27 2019 *)
  • PARI
    { T(n,k) = my(X=x+x*O(x^n),Y=y+y*O(y^k)); polcoeff(polcoeff((1 + X^2)/(1-X-X^2 + X*Y),n,x),k,y); }
  • PARI
    { tabl(nn) = my(m = matrix(nn, nn, n, k, n--; k--; if((nMichel Marcus, Jun 30 2015
  • PARI
    { A104509(n,k) = if(n==0, k==0, (-1)^k * sum(i=0, (n-k)\2, n/(n-i) * binomial(n-k-i,i) * binomial(n-i,k) )); } \\ Max Alekseyev, Oct 11 2021

Formula

For n>=1, a(n,k) = (-1)^k * Sum_{i=0..[(n-k)/2]} n/(n-i) * binomial(n-i,i) * binomial(n-2*i,k) = (-1)^k * Sum_{i=0..[(n-k)/2]} n/(n-i) * binomial(n-k-i,i) * binomial(n-i,k). - Max Alekseyev, Oct 11 2021
G.f.: A(x, y) = (1 + x^2)/(1-x-x^2 + x*y).
G.f. for column k: g_k(x) = -(x^2+1)*x^k/(x^2+x-1)^(k+1). - Robert Israel, Jun 30 2015
G.f. for row n>=1 is the Lucas polynomial L_n(1-x). - Max Alekseyev, Oct 11 2021

A309220 Square array A read by antidiagonals: the columns are given by A(n,1)=1, A(n,2)=n+1, A(n,3) = n^2+2n+3, A(n,4) = n^3+3*n^2+6*n+4, A(n,5) = n^4+4*n^3+10*n^2+12*n+7, ..., whose coefficients are given by A104509 (see also A118981).

Original entry on oeis.org

1, 1, 2, 1, 3, 6, 1, 4, 11, 14, 1, 5, 18, 36, 34, 1, 6, 27, 76, 119, 82, 1, 7, 38, 140, 322, 393, 198, 1, 8, 51, 234, 727, 1364, 1298, 478, 1, 9, 66, 364, 1442, 3775, 5778, 4287, 1154, 1, 10, 83, 536, 2599, 8886, 19602, 24476, 14159, 2786, 1, 11, 102, 756, 4354, 18557
Offset: 1

Views

Author

N. J. A. Sloane, Aug 12 2019, based on R. J. Mathar's 2011 analysis of A118980

Keywords

Comments

As pointed out by Peter Munn, A117938 gives the same triangle, except that it has an additional diagonal at the right. - N. J. A. Sloane, Aug 13 2019

Examples

			The first few antidiagonals are:
1,
1,2,
1,3,6,
1,4,11,14,
1,5,18,36,34,
1,6,27,76,119,82,
1,7,38,140,322,393,198,
...
The first nine rows of A are
1, 2, 6, 14, 34, 82, 198, 478, 1154, 2786, 6726, 16238, ...
1, 3, 11, 36, 119, 393, 1298, 4287, 14159, 46764, 154451, 510117, ...
1, 4, 18, 76, 322, 1364, 5778, 24476, 103682, 439204, 1860498, 7881196, ...
1, 5, 27, 140, 727, 3775, 19602, 101785, 528527, 2744420, 14250627, 73997555, ...
1, 6, 38, 234, 1442, 8886, 54758, 337434, 2079362, 12813606, 78960998, 486579594, ...
1, 7, 51, 364, 2599, 18557, 132498, 946043, 6754799, 48229636, 344362251, 2458765393, ...
1, 8, 66, 536, 4354, 35368, 287298, 2333752, 18957314, 153992264, 1250895426, 10161155672, ...
1, 9, 83, 756, 6887, 62739, 571538, 5206581, 47430767, 432083484, 3936182123, 35857722591, ...
1, 10, 102, 1030, 10402, 105050, 1060902, 10714070, 108201602, 1092730090, 11035502502, 111447755110, ...

Crossrefs

Cf. A104509, A117938, A118980, A118981, A099425 (top row), A006497 (essentially the 2nd row), A014448 (essentially the 3rd row), A087130 (essentially the 4th row).

Programs

  • Maple
    M := 12;
A:=Array(1..2*M,1..2*M,0):
for i from 1 to M do A[i,1]:=1; od:
S := series((1 + x^2)/(1-x-x^2 + x*y), x, 120): # this is g.f. for A104509
for n from 1 to M do
R2 := expand(coeff(S, x, n));
R3 := [seq(abs(coeff(R2,y,n-i)),i=0..n)];
f := k-> add( R3[i]*k^(n-i+1), i=1..nops(R3) ): # this is the formula for the (n+1)-st column
s1 := [seq(f(i),i=1..M)];
for i from 1 to M do A[i,n+1]:=s1[i]; od:
od:
for i from 1 to M do lprint([seq(A[i,j],j=1..M)]); od:
# alternative by R. J. Mathar, Aug 13 2019 :
A104509 := proc(n,k)
    (1+x^2)/(1-x-x^2+x*y) ;
    coeftayl(%,x=0,n) ;
    coeftayl(%,y=0,k) ;
end proc:
A309220 := proc(n::integer,k::integer)
    local x;
    add( abs(A104509(k-1,i))*x^i,i=0..k-1) ;
    subs(x=n,%) ;
end proc:
seq( seq(A309220(d-k,k),k=1..d-1),d=2..13) ;

A118980 Triangle read by rows: rows = inverse binomial transforms of columns of A309220.

Original entry on oeis.org

1, 2, 1, 6, 5, 2, 14, 22, 18, 6, 34, 85, 118, 84, 24, 82, 311, 660, 780, 480, 120, 198, 1100, 3380, 5964, 6024, 3240, 720, 478, 3809, 16380, 40740, 60480, 52920, 25200, 5040, 1154, 13005, 76518, 258804, 531864, 676080, 519840, 221760, 40320, 2786, 43978, 348462, 1564314, 4286880, 7444800, 8240400
Offset: 1

Views

Author

Gary W. Adamson, May 07 2006

Keywords

Comments

First few columns of A309220:
1, 2, 6, 14, 34, ...
1, 3, 11, 36, 119, ...
1, 4, 18, 76, 322, ...
1, 5, 27, 140, 727, ...
1, 6, 38, 234, 1442, ...
1, 7, 51, 364, 2599, ...
1, 8, 66, 536, 4354, ...
...

Examples

			First few rows of the triangle:
   1;
   2,   1;
   6,   5,   2;
  14,  22,  18,   6;
  34,  85, 118,  84,  24;
  82, 311, 660, 780, 480, 120;
  ...
Column 3 of A309220 = (6, 11, 18, 27, 38, 51, ...), whose inverse binomial transform is (6, 5, 2).

Crossrefs

The leading column is A099425, and the rightmost two diagonals are A038720 and A000142.
Cf. A104509, A117938, A118981, A309220.

Programs

  • Maple
    with(transforms);
M := 12;
T := [1];
S := series((1 + x^2)/(1-x-x^2 + x*y), x, 120):
for n from 1 to M do
R2 := expand(coeff(S, x, n));
R3 := [seq(abs(coeff(R2,y,n-i)),i=0..n)];
f := k-> add( R3[i]*k^(n-i+1), i=1..nops(R3) ):
s1 := [seq(f(i),i=1..3*n)];
s2 := BINOMIALi(s1);
s3 := [seq(s2[i],i=1..n+1)];
T := [op(T), op(s3)];
od:
T;  # N. J. A. Sloane, Aug 12 2019

Extensions

Edited and extended by N. J. A. Sloane, Aug 12 2019, guided by the comments of R. J. Mathar from Oct 30 2011
Showing 1-5 of 5 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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