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 1-9 of 9 results.

A091742 Second column (m=1) of triangle A060063.

Original entry on oeis.org

1, 26, 775, 32516, 1894429, 148008446, 15005570563, 1920091871816, 303034557325177, 57867367557774626, 13156672434190398271, 3513034745241511676876, 1088776741031904909773845
Offset: 1

Views

Author

Wolfdieter Lang, Feb 13 2004

Keywords

Formula

a(n)= A060063(n, 1), n>=1.

A091743 Third column (m=2) of triangle A060063 divided by 9.

Original entry on oeis.org

1, 131, 12702, 1331426, 163594663, 23979017805, 4187448766444, 864808560876788, 209300424292684605, 58811116750666789895, 19017126570296402361706, 7018937700334256743262646
Offset: 2

Views

Author

Wolfdieter Lang, Feb 13 2004

Keywords

Formula

a(n)= A060063(n, 2)/9, n>=2.

A091744 Fourth column (m=3) of triangle A060063 divided by 9.

Original entry on oeis.org

25, 9684, 2263474, 490886452, 111812888083, 27999019489624, 7844432790401028, 2473024180429410040, 877529810239038245325, 349669921564112871530060, 155914953071171948587819830, 77481281483613804213513143564
Offset: 3

Views

Author

Wolfdieter Lang, Feb 13 2004

Keywords

A091745 Alternating row sums of triangle A060063.

Original entry on oeis.org

1, 0, -12, 240, 7056, -1472640, 60785472, 24634471680, -6666732039936, -266945607045120, 818181307311879168, -225753930347735961600, -114700401016766429097984, 133755245359458345703342080
Offset: 0

Views

Author

Wolfdieter Lang, Feb 13 2004

Keywords

Formula

a(n)=sum(A060063(n, m)*(-1)^m, m=0..n), n>=0.

A052502 Number of permutations sigma of [3n] without fixed points such that sigma^3 = Id.

Original entry on oeis.org

1, 2, 40, 2240, 246400, 44844800, 12197785600, 4635158528000, 2345390215168000, 1524503639859200000, 1237896955565670400000, 1227993779921145036800000, 1461312598106162593792000000, 2054605512937264606871552000000
Offset: 0

Views

Author

encyclopedia(AT)pommard.inria.fr, Jan 25 2000

Keywords

Comments

For n >= 1 a(n) is the size of the conjugacy class in the symmetric group S_(3n) consisting of permutations whose cycle decomposition is a product of n disjoint 3-cycles.

References

  • F. W. J. Olver, Asymptotics and special functions, Academic Press, 1974, pages 336-344.

Crossrefs

Cf. A000142. Row sums of triangle A060063.
First column of array A091752 (also negative of second column).
Equals row sums of A157702. - Johannes W. Meijer, Mar 07 2009
Karol A. Penson suggested that the row sums of A060063 coincide with this entry.
Trisection of column k=3 of A261430.

Programs

  • GAP
    List([0..20], n-> Factorial(3*n)/(3^n*Factorial(n))) # G. C. Greubel, May 14 2019
  • Magma
    [Factorial(3*n)/(3^n*Factorial(n)): n in [0..20]]; // G. C. Greubel, May 14 2019
    
  • Maple
    spec := [S,{S=Set(Union(Cycle(Z,card=3)))},labeled]: seq(combstruct[count](spec,size=n), n=0..20);
  • Mathematica
    Table[(3*n)!/(3^n*n!), {n, 0, 20}] (* G. C. Greubel, May 14 2019 *)
  • PARI
    {a(n) = (3*n)!/(3^n*n!)}; \\ G. C. Greubel, May 14 2019
    
  • Sage
    [factorial(3*n)/(3^n*factorial(n)) for n in (0..20)] # G. C. Greubel, May 14 2019
    

Formula

From Ahmed Fares (ahmedfares(AT)my-deja.com), Apr 21 2001: (Start)
a(n) = (3*n)!/(3^n * n!).
a(n) ~ sqrt(3) * 9^n * (n/e)^(2n). (End)
E.g.f.: (every third coefficient of) exp(x^3/3).
G.f.: hypergeometric3F0([1/3, 2/3, 1], [], 9*x).
D-finite with recurrence a(n) = (3*n-1)*(3*n-2)*a(n-1) for n >= 1, with a(0) = 1.
Write the generating function for this sequence in the form A(x) = Sum_{n >= 0} a(n)* x^(2*n+1)/(2*n+1)!. The g.f. A(x) satisfies A'(x)*( 1 - A(x)^2) = 1. Robert Israel remarks that consequently A(x) is a root of z^3 - 3*z + 3*x with A(0) = 0. Cf. A001147, A052504 and A060706. - Peter Bala, Jan 02 2015
From Peter Bala, Feb 27 2024: (Start)
u(n) := a(n+1) satisfies the second-order recurrence u(n) = 18*n*u(n-1) + (3*n - 1)^2*(3*n - 2)^2*u(n-2) with u(0) = 2 and u(1) = 40.
A second solution to the recurrence is given by v(n) := u(n)*Sum_{k = 0..n} (-1)^k/((3*k + 1)*(3*k + 2)) with v(0) = 1 and v(1) = 18.
This leads to the continued fraction expansion (2/3)*log(2) = Sum_{k = 0..n} (-1)^k/((3*k + 1)*(3*k + 2)) = Limit_{n -> oo} v(n)/u(n) = 1/(2 + (1*2)^2/(18 + (4*5)^2/(2*18 + (7*8)^2/(3*18 + (10*11)^2/(4*18 + ... ))))). (End)
From Gabriel B. Apolinario, Jul 30 2024: (Start)
a(n) = 3 * Integral_{t=0..oo} Ai(t)*t^(3*n) dt, where Ai(t) is the Airy function.
a(n) = Integral_{t=-oo..oo} Ai(t)*t^(3*n) dt. (End)

Extensions

Edited by Wolfdieter Lang, Feb 13 2004
Title improved by Geoffrey Critzer, Aug 14 2015

A060058 Triangle of numbers related to A000330 (sum of squares) and A000364 (Euler numbers).

Original entry on oeis.org

1, 1, 1, 1, 5, 5, 1, 14, 61, 61, 1, 30, 331, 1385, 1385, 1, 55, 1211, 12284, 50521, 50521, 1, 91, 3486, 68060, 663061, 2702765, 2702765, 1, 140, 8526, 281210, 5162421, 49164554, 199360981, 199360981, 1, 204, 18522, 948002, 28862471, 510964090, 4798037791, 19391512145, 19391512145
Offset: 0

Views

Author

Wolfdieter Lang, Mar 16 2001

Keywords

Examples

			Triangle T(n, k) starts:
  [0] 1;
  [1] 1,   1;
  [2] 1,   5,    5;
  [3] 1,  14,   61,     61;
  [4] 1,  30,  331,   1385,    1385;
  [5] 1,  55, 1211,  12284,   50521,    50521;
  [6] 1,  91, 3486,  68060,  663061,  2702765,   2702765;
  [7] 1, 140, 8526, 281210, 5162421, 49164554, 199360981, 199360981;
  ...
		

Crossrefs

Cf. A060059 (row sums), A000364 (main diagonal Euler numbers).
Columns: A000012 (powers of 1), A000330 (sum of squares), A060060-2 for m=0,...,4.
See triangle A060074.

Programs

  • Maple
    T := proc(n, k) option remember; if k = 0 then 1 else if k = n then T(n, k-1) else (n - k + 1)^2 * T(n, k - 1) + T(n - 1, k) fi fi end:
    seq(print(seq(T(n, k), k=0..n)), n=0..7);  # Peter Luschny, Sep 30 2023
  • Mathematica
    a[, -1] = 0; a[0, 0] = 1; a[n, m_] /; n < m = 0; a[n_, m_] := a[n, m] = a[n-1, m] + (n+1-m)^2*a[n, m-1]; Table[a[n, m], {n, 0, 8}, {m, 0, n}] // Flatten (* Jean-François Alcover, Jul 09 2013 *)

Formula

a(n, m) = a(n-1, m) + ((n+1-m)^2)*a(n, m-1), a(n, -1) := 0, a(0, 0) = 1, a(n, m) = 0 if n < m.
a(n, m) = ay(n-m+1, m) if n >= m >= 0, with the rectangular array ay(n, m) := Sum_{j=1..n} (j^2)*ay(j+1, m-1), n >= 0, m >= 1; input: ay(n, 0)=1 (iterated sums of squares).
G.f. for m-th column: 1/(1-x) for m=0, (x^m)*(Sum_{k=0..m} A060063(m, k)*x^k)/(1-x)^(3*m+1), m >= 1.
Recursion for g.f.s for m-th column: (1-x)*G(m, x) = x*G''(m-1, x) - G'(m-1, x) + G(m-1, x)/x, m >= 2; G(1, x) = x*(1+x)/(1-x)^4; the apostrophe denotes differentiation w.r.t. x. G(0, x) = 1/(1-x). - Wolfdieter Lang, Feb 13 2004

A060061 Fourth column of triangle A060058.

Original entry on oeis.org

61, 1385, 12284, 68060, 281210, 948002, 2749340, 7097948, 16700255, 36419955, 74551048, 144631240, 267951892, 476948260, 819683560, 1365672424, 2213323585, 3499318141, 5410278500, 8197124100
Offset: 0

Views

Author

Wolfdieter Lang, Mar 16 2001

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Binomial[n+6,6]*(280*n^3+2436*n^2+5906n+3843)/63,{n,0,19}] (* Indranil Ghosh, Feb 21 2017 *)
  • Python
    import math
    def C(n, r):
        f=math.factorial
        return f(n)//f(r)//f(n-r)
    def A060061(n):
        return (C(n+6, 6)*(280*n**3+2436*n**2+5906*n+3843))//63 # Indranil Ghosh, Feb 21 2017

Formula

a(n) = Sum_{j3=1..n+1} j3^2*Sum_{j2=1..j3+1} j2^2*Sum_{j1=1..j2+1} j1^2.
a(n) = A060058(n+3, 3) = binomial(n+6, 6)*(280*n^3+2436*n^2+5906*n+3843)/(7*9).
G.f.: (61+775*x+1179*x^2+225*x^3)/(1-x)^10 = p(3, x)/(1-x)^(3*3+1) with p(3, x)=sum(A060063(3, m)*x^m, m=0..3).

A060060 Third column of triangle A060058.

Original entry on oeis.org

5, 61, 331, 1211, 3486, 8526, 18522, 36762, 67947, 118547, 197197, 315133, 486668, 729708, 1066308, 1523268, 2132769, 2933049, 3969119, 5293519, 6967114, 9059930, 11652030, 14834430, 18710055, 23394735
Offset: 0

Views

Author

Wolfdieter Lang, Mar 16 2001

Keywords

Examples

			a(3) = binomial(7,4) * (20 * 3^2 + 88*3 +75) / 15 = (35 * 519)/15 = 1211. - _Indranil Ghosh_, Feb 21 2017
		

Programs

  • Mathematica
    Table[(Binomial[n+4,4]*(20*n^2+88*n+75)/15),{n,0,25}] (* Indranil Ghosh, Feb 21 2017 *)
  • Python
    import math
    def C(n, r):
        f=math.factorial
        return f(n)//f(r)//f(n-r)
    def A060060(n):
        return C(n+4, 4)*(20*n**2+88*n+75)//15 # Indranil Ghosh, Feb 21 2017

Formula

a(n) = A060058(n+2, 2) = binomial(n+4, 4)*(20*n^2+88*n+75)/(3*5).
G.f.: (5+26*x+9*x^2)/(1-x)^7 = p(2, x)/(1-x)^(2*3+1). p(2, x)=sum(A060063(2, m)*x^m, m=0..2).

A060062 Fifth column of triangle A060058.

Original entry on oeis.org

1385, 50521, 663061, 5162421, 28862471, 127838711, 475638163, 1544454483, 4494470838, 11949575638, 29449955678, 68035028126, 148639284066, 309297261826, 616573557226, 1183184394986, 2194487337735, 3947417571735, 6906579371835, 11783600663835, 19647572529585
Offset: 0

Views

Author

Wolfdieter Lang, Mar 16 2001

Keywords

Comments

Fourfold iterated sums of squares; see A060061 for threefold case.

Programs

  • Mathematica
    CoefficientList[Series[(1385+32516*x+114318*x^2+87156*x^3+11025*x^4)/(1-x)^13 ,{x,0,20}],x] (* Indranil Ghosh, Feb 21 2017 *)

Formula

G.f. (1385+32516*x+114318*x^2+87156*x^3+11025*x^4)/(1-x)^13 = p(4, x)/(1-x)^(4*3+1) with p(2, x)=sum(A060063(4, m)*x^m, m=0..4).
Showing 1-9 of 9 results.