Original entry on oeis.org
1, 3, 30, 1050, 132300, 61122600, 104886381600, 674943865596000, 16407885372638760000, 1515727634953623371280000, 534621388490302221024396480000, 722849817707190846398223943885440000, 3759035907022704558524683975387453632000000
Offset: 1
-
[(&*[Binomial(2*n-k,k): k in [1..n]]): n in [1..20]]; // G. C. Greubel, Aug 29 2023
-
(* First program *)
f[j_]:= j; z = 16;
v[n_]:= Product[Product[f[k] + f[j], {j,k-1}], {k,2,n}]
d[n_]:= Product[(i-1)!, {i,n}]
Table[v[n], {n,z}] (* A093883 *)
Table[v[n+1]/v[n], {n,z-1}] (* A006963 *)
Table[v[n]/d[n], {n,20}] (* A203469 *)
(* Second program *)
Table[Product[Binomial[2*n-j,j], {j,n}], {n,20}] (* G. C. Greubel, Aug 29 2023 *)
-
[product(binomial(2*n-j,j) for j in range(n)) for n in range(1, 20)] # G. C. Greubel, Aug 29 2023
A218566
Triangle T[r,c]=(r-1)*binomial(r-1,c-1)*(c-1)!*A093883(c), read by rows.
Original entry on oeis.org
0, 1, 3, 2, 12, 240, 3, 27, 1080, 226800, 4, 48, 2880, 1209600, 3657830400, 5, 75, 6000, 3780000, 22861440000, 1267438233600000, 6, 108, 10800, 9072000, 82301184000, 9125555281920000, 11274806061917798400000
Offset: 1
The first 6 rows of the triangle are:
r=1: 0;
r=2: 1, 3;
r=3: 2, 12, 240;
r=4: 3, 27, 1080, 226800;
r=5: 4, 48, 2880, 1209600, 3657830400;
r=6: 5, 75, 6000, 3780000, 22861440000, 1267438233600000.
Row 2 counts the numbers 1 and 4=100[2], 5=101[2], 6=110[2].
Row 3 counts the numbers {1, 2} and {9=100[3], 10=101[3], 12=110[3], 14=112[3], 16=121[3], ..., 25=221[3]} and {248=100012[3], ..., 714=222110[3]}.
A006963
Number of planar embedded labeled trees with n nodes: (2*n-3)!/(n-1)! for n >= 2, a(1) = 1.
Original entry on oeis.org
1, 1, 3, 20, 210, 3024, 55440, 1235520, 32432400, 980179200, 33522128640, 1279935820800, 53970627110400, 2490952020480000, 124903451312640000, 6761440164390912000, 393008709555221760000, 24412776311194951680000, 1613955767240110694400000
Offset: 1
G.f. = x + x^2 + 3*x^3 + 20*x^4 + 210*x^5 + 3024*x^6 + 55440*x^7 + 1235520*x^8 + ...
a(5) = 210 = 30 + 60 + 120 where 30 is for the star, 60 for the path, and 120 for the tree with one trivalent vertex. - _Michael Somos_, Aug 19 2014
- N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
- Vincenzo Librandi, Table of n, a(n) for n = 1..200
- David Callan, A quick count of plane (or planar embedded) labeled trees.
- Ali Chouria, Vlad-Florin Drǎgoi, and Jean-Gabriel Luque, On recursively defined combinatorial classes and labelled trees, arXiv:2004.04203 [math.CO], 2020.
- Robert Coquereaux and Jean-Bernard Zuber, Maps, immersions and permutations, Journal of Knot Theory and Its Ramifications, Vol. 25, No. 8 (2016), 1650047; arXiv preprint, arXiv:1507.03163 [math.CO], 2015-2016.
- INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 109.
- Bradley Robert Jones, On tree hook length formulas, Feynman rules and B-series, Master's thesis, Simon Fraser University, 2014.
- Pierre Leroux and Brahim Miloudi, Généralisations de la formule d'Otter, Ann. Sci. Math. Québec, Vol. 16, No. 1 (1992), pp. 53-80.
- Pierre Leroux and Brahim Miloudi, Généralisations de la formule d'Otter, Ann. Sci. Math. Québec, Vol. 16, No. 1 (1992), pp. 53-80. (Annotated scanned copy)
- J. W. Moon, Counting Labelled Trees, Issue 1 of Canadian mathematical monographs, Canadian Mathematical Congress, 1970.
- Ran J. Tessler, A Cayley-type identity for trees, arXiv:1809.00001 [math.CO], 2018.
- Index entries for sequences related to trees.
-
[1] cat [Factorial(2*n-3)/Factorial(n-1): n in [2..20]]; // Vincenzo Librandi, Nov 12 2011
-
1, seq((2*n-3)!/(n-1)!,n=2..30); # Robert Israel, Aug 20 2014
-
Join[{1},Table[(2n-3)!/(n-1)!,{n,2,20}]] (* Harvey P. Dale, Nov 03 2011 *)
a[ n_] := With[{m = n - 1}, If[m < 1, Boole[m == 0], m! SeriesCoefficient[ -Log[(1 + Sqrt[1 - 4 x]) / 2], {x, 0, m}]]] (* Michael Somos, Jul 01 2013 *)
a[ n_] := If[n < 2, Boole[n == 1], (2 n - 3)! / (n - 1)!]; (* Michael Somos, Aug 19 2014 *)
a[1] := 1; a[n_] := (-1)^(n - 1)*Sum[(-1)^k*Binomial[2*n - 3, n + k - 2]*StirlingS1[n + k - 1, k + 1], {k, 1, n - 1}]; Flatten[Table[a[n], {n, 1, 19}]] (* Detlef Meya, Jan 18 2024 *)
-
{a(n) = n--; if( n<1, n==0, n! * polcoeff( -log( (1 + sqrt(1 - 4*x + x * O(x^n))) / 2), n))}; /* Michael Somos, Jul 01 2013 */
-
def A006963(n): return 1 if n==1 else factorial(2*n-3)/factorial(n-1)
[A006963(n) for n in range(1,31)] # G. C. Greubel, May 23 2023
A203312
Vandermonde sequence using x^2 - xy + y^2 applied to (1,2,...,n).
Original entry on oeis.org
1, 3, 147, 298116, 47460365316, 965460013501733568, 3717096745012192786213464768, 3763515081241454304168766426610670649344, 1329626784930718063722475681347135527472012731205697536
Offset: 1
-
f[j_] := j; z = 12;
v[n_] := Product[Product[f[j]^2 - f[j] f[k] + f[k]^2,
{j, 1, k - 1}], {k, 2, n}]
Table[v[n], {n, 1, z}] (* A203312 *)
Table[v[n + 1]/v[n], {n, 1, z}] (* A203513 *)
-
from operator import mul
from functools import reduce
def v(n): return 1 if n==1 else reduce(mul, [j**2 - j*k + k**2 for k in range(2, n + 1) for j in range(1, k)])
print([v(n) for n in range(1, 11)]) # Indranil Ghosh, Jul 26 2017
A203475
a(n) = Product_{1 <= i < j <= n} (i^2 + j^2).
Original entry on oeis.org
1, 5, 650, 5525000, 5807194900000, 1226800120038480000000, 77092420109247492627600000000000, 2001314057760220784660590245696000000000000000, 28468550112906756205383102673584071297339520000000000000000000
Offset: 1
-
[(&*[(&*[j^2 + k^2: k in [1..j]])/(2*j^2): j in [1..n]]): n in [1..20]]; // G. C. Greubel, Aug 28 2023
-
a:= n-> mul(mul(i^2+j^2, i=1..j-1), j=2..n):
seq(a(n), n=1..10); # Alois P. Heinz, Jul 23 2017
-
f[j_]:= j^2; z = 15;
v[n_]:= Product[Product[f[k] + f[j], {j,k-1}], {k,2,n}]
Table[v[n], {n,z}] (* A203475 *)
Table[v[n+1]/v[n], {n,z-1}] (* A203476 *)
-
[product(product(j^2+k^2 for k in range(1,j)) for j in range(1,n+1)) for n in range(1,21)] # G. C. Greubel, Aug 28 2023
A203673
Vandermonde sequence using x^2 + xy + y^2 applied to (1,4,9,...,n^2).
Original entry on oeis.org
1, 21, 254163, 11213968422384, 6451450005117349260375984, 127857993263632065817610313129228311433216, 191199773886534869435599958788731398661833328276349525268803584
Offset: 1
-
f[j_] := j^2; z = 12;
u[n_] := Product[f[j]^2 + f[j] f[k] + f[k]^2, {j, 1, k - 1}]
v[n_] := Product[u[n], {k, 2, n}]
Table[v[n], {n, 1, z}] (* A203673 *)
Table[v[n + 1]/v[n], {n, 1, z}] (* A203674 *)
A080358
Value of Vandermonde determinant for the first n prime numbers: V[prime(1), ..., prime(n)].
Original entry on oeis.org
1, 1, 1, 6, 240, 414720, 4379443200, 2648687247360000, 11619303595714805760000, 4047756373260469165621248000000, 311107430628520522709128328175943680000000, 152539657943794787580793302587123569672794931200000000
Offset: 0
a(1)=1 corresponds to 1 X 1 V-matrix, while a(2)=1 is computed from a 2 X 2 matrix.
n = 2: a(2) = prime(2) - prime(1) = 3 - 2 = 1;
n = 3: a(3) = (5-3)*(5-2)*(3-2) = 2*3*1 = 6; ...
n = 6: a(6) = (13-11)*(13-7)*(13-5)*(13-3)*(13-2)*(11-7)*(11-5)*(11-3)*(11-2)*(7-5)*(7-3)*(7-2)*(5-3)*(5-2)*(3-2) = 2*6*8*10*11*4*6*8*9*2*4*5*2*3*1 = 10560*1728*40*6*1 = 4379443200.
-
with(LinearAlgebra):
a:= n-> Determinant(Matrix(n, (i,j)-> ithprime(i)^(j-1))):
seq(a(n), n=0..15); # Alois P. Heinz, Jul 22 2017
-
b[x_] := Prime[x] d[x_] := b[x+1]-b[x] t[m_] := b[m+1]-Table[b[x], {x, 1, m}] pt[x_] := Apply[Times, t[x]] va[x_] := Apply[Times, Table[pt[w], {w, 1, x}]] Table[va[j], {j, 1, 10}]
A203012
Vandermonde sequence using x^2 + xy + y^2 applied to (1,2,...,n).
Original entry on oeis.org
1, 7, 1729, 37616124, 135933424914924, 132432199651531695045312, 51437933151214684812682944045953088, 11056394929890243558409721156996503083526683082752, 1743892714865607005898689849291524734866677095031979100765833773056
Offset: 1
a(1)=1
a(2)=1^2+1*2+2^2=7
a(3)=(1^2+1*2+2^2)(1^3+1*3+3^2)(2^2+2*3+3^2)=1729.
-
f[j_] := j; z = 12;
v[n_] := Product[Product[f[j]^2 + f[j] f[k] + f[k]^2,
{j, 1, k - 1}], {k, 2, n}]
Table[v[n], {n, 1, z}] (* A203012 *)
Table[v[n + 1]/v[n], {n, 1, z}] (* A203158 *)
A203311
Vandermonde determinant of (1,2,3,...,F(n+1)), where F=A000045 (Fibonacci numbers).
Original entry on oeis.org
1, 1, 1, 2, 48, 30240, 1596672000, 18172937502720000, 122457316443772566896640000, 1284319496829094129116119090331648000000, 55603466527142141932748234118927499493985767915520000000, 26110840958525805673462196263372614726154694067746586937781385166848000000000
Offset: 0
v(4) = (2-1)*(3-1)*(3-2)*(5-1)*(5-2)*(5-3).
-
with(LinearAlgebra): F:= combinat[fibonacci]:
a:= n-> Determinant(VandermondeMatrix([F(i)$i=2..n+1])):
seq(a(n), n=0..12); # Alois P. Heinz, Jul 23 2017
-
f[j_] := Fibonacci[j + 1]; z = 15;
v[n_] := Product[Product[f[k] - f[j], {j, 1, k - 1}], {k, 2, n}]
d[n_] := Product[(i - 1)!, {i, 1, n}]
Table[v[n], {n, 1, z}] (* A203311 *)
Table[v[n + 1]/v[n], {n, 1, z - 1}] (* A123741 *)
Table[v[n]/d[n], {n, 1, 13}] (* A203313 *)
-
from sympy import fibonacci, factorial
from operator import mul
from functools import reduce
def f(j): return fibonacci(j + 1)
def v(n): return 1 if n==1 else reduce(mul, [reduce(mul, [f(k) - f(j) for j in range(1, k)]) for k in range(2, n + 1)])
print([v(n) for n in range(1, 16)]) # Indranil Ghosh, Jul 26 2017
A203482
a(n) = Product_{1 <= i < j <= n} (i! + j!).
Original entry on oeis.org
1, 3, 168, 3276000, 877449500928000, 207244701437748852512194560000, 4000516840149319128119305958853265913416777728000000, 796608816253064941944831363792070377592412324940256242675178274726476775424000000000
Offset: 1
-
[(&*[(&*[Factorial(j) + Factorial(k): k in [1..j]])/(2*Factorial(j)): j in [1..n]]): n in [1..20]]; // G. C. Greubel, Aug 29 2023
-
a:= n-> mul(mul(i!+j!, i=1..j-1), j=2..n):
seq(a(n), n=1..10); # Alois P. Heinz, Jul 23 2017
-
(* First program *)
f[j_]:= j!; z = 10;
v[n_]:= Product[Product[f[k] + f[j], {j, k-1}], {k, 2, n}]
d[n_]:= Product[(i-1)!, {i, n}] (* A000178 *)
Table[v[n], {n, z}] (* A203482 *)
Table[v[n+1]/v[n], {n, z-1}] (* A203483 *)
Table[v[n]/d[n], {n, 10}] (* A203510 *)
(* Second program *)
Table[Product[j!+k!, {j,n}, {k,j-1}], {n,15}] (* G. C. Greubel, Aug 29 2023 *)
-
[product(product(factorial(j) + factorial(k) for k in range(1,j)) for j in range(1,n+1)) for n in range(1,16)] # G. C. Greubel, Aug 29 2023
Showing 1-10 of 115 results.
Comments