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.

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A346415 Triangle T(n,k), n>=0, 0<=k<=n, read by rows, where column k is (1/k!) times the k-fold exponential convolution of Fibonacci numbers with themselves.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 2, 3, 1, 0, 3, 11, 6, 1, 0, 5, 35, 35, 10, 1, 0, 8, 115, 180, 85, 15, 1, 0, 13, 371, 910, 630, 175, 21, 1, 0, 21, 1203, 4494, 4445, 1750, 322, 28, 1, 0, 34, 3891, 22049, 30282, 16275, 4158, 546, 36, 1, 0, 55, 12595, 107580, 202565, 144375, 49035, 8820, 870, 45, 1
Offset: 0

Views

Author

Alois P. Heinz, Jul 15 2021

Keywords

Comments

The sequence of column k>0 satisfies a linear recurrence with constant coefficients of order k+1.

Examples

			Triangle T(n,k) begins:
  1;
  0,  1;
  0,  1,     1;
  0,  2,     3,      1;
  0,  3,    11,      6,      1;
  0,  5,    35,     35,     10,      1;
  0,  8,   115,    180,     85,     15,     1;
  0, 13,   371,    910,    630,    175,    21,    1;
  0, 21,  1203,   4494,   4445,   1750,   322,   28,   1;
  0, 34,  3891,  22049,  30282,  16275,  4158,  546,  36,  1;
  0, 55, 12595, 107580, 202565, 144375, 49035, 8820, 870, 45, 1;
  ...
		

Crossrefs

Columns k=0-4 give: A000007, A000045, A014335, A014337, A014341.
T(n+j,n) for j=0-2 give: A000012, A000217, A000914.
Row sums give A256180.

Programs

  • Maple
    b:= proc(n) option remember; `if`(n=0, 1, add(expand(x*b(n-j)
          *binomial(n-1, j-1)*(<<0|1>, <1|1>>^j)[1, 2]), j=1..n))
        end:
    T:= n-> (p-> seq(coeff(p, x, i), i=0..n))(b(n)):
    seq(T(n), n=0..12);
    # second Maple program:
    b:= proc(n, k) option remember; `if`(k=0, 0^n, `if`(k=1,
           combinat[fibonacci](n), (q-> add(binomial(n, j)*
           b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2))))
        end:
    T:= (n, k)-> b(n, k)/k!:
    seq(seq(T(n, k), k=0..n), n=0..12);
  • Mathematica
    b[n_, k_] := b[n, k] = If[k == 0, 0^n, If[k == 1, Fibonacci[n], With[{q = Quotient[k, 2]}, Sum[Binomial[n, j] b[j, q] b[n-j, k-q], {j, 0, n}]]]];
    T[n_, k_] := b[n, k]/k!;
    Table[Table[T[n, k], {k, 0, n}], {n, 0, 12}] // Flatten (* Jean-François Alcover, Nov 06 2021, after 2nd Maple program *)

A347107 a(n) = Sum_{1 <= i < j <= n} j^3*i^3.

Original entry on oeis.org

0, 0, 8, 251, 2555, 15055, 63655, 214918, 616326, 1561110, 3586110, 7612385, 15139553, 28506101, 51229165, 88438540, 147420940, 238291788, 374813076, 575377095, 864177095, 1272587195, 1840775123, 2619572626, 3672629650, 5078879650, 6935344650, 9360309933
Offset: 0

Views

Author

Roudy El Haddad, Jan 27 2022

Keywords

Comments

a(n) is the sum of all products of two distinct cubes of positive integers up to n, i.e., the sum of all products of two distinct elements from the set of cubes {1^3, ..., n^3}.

Examples

			For n=3, a(3) = (2*1)^3+(3*1)^3+(3*2)^3 = 251.
		

Crossrefs

Cf. A346642 (for nondistinct cubes).
Cf. A000217 (for power 0), A000914 (for power 1), A000596 (for squares).

Programs

  • Mathematica
    CoefficientList[Series[-(x^5 + 64 x^4 + 424 x^3 + 584 x^2 + 179 x + 8) x^2/(x - 1)^9, {x, 0, 27}], x] (* Michael De Vlieger, Feb 04 2022 *)
    LinearRecurrence[{9,-36,84,-126,126,-84,36,-9,1},{0,0,8,251,2555,15055,63655,214918,616326},30] (* Harvey P. Dale, Jul 07 2025 *)
  • PARI
    a(n) = sum(i=2, n, sum(j=1, i-1, i^3*j^3));
    
  • PARI
    {a(n) = n*(n+1)*(n-1)*(21*n^5+36*n^4-21*n^3-48*n^2+8)/672};
    
  • Python
    def A347107(n): return n*(n**2*(n*(n*(n*(n*(21*n + 36) - 42) - 84) + 21) + 56) - 8)//672 # Chai Wah Wu, Feb 17 2022

Formula

a(n) = Sum_{j=2..n} Sum_{i=1..j-1} j^3*i^3.
a(n) = n*(n+1)*(n-1)*(21*n^5+36*n^4-21*n^3-48*n^2+8)/672 (from the generalized form of Faulhaber's formula).
From Alois P. Heinz, Jan 27 2022: (Start)
a(n) = Sum_{i=1..n} A000578(i)*A000537(i-1) = Sum_{i=1..n} i^3*(i*(i-1)/2)^2.
G.f.: -(x^5+64*x^4+424*x^3+584*x^2+179*x+8)*x^2/(x-1)^9. (End)

A103115 a(n) = 6*n*(n-1) - 1.

Original entry on oeis.org

-1, -1, 11, 35, 71, 119, 179, 251, 335, 431, 539, 659, 791, 935, 1091, 1259, 1439, 1631, 1835, 2051, 2279, 2519, 2771, 3035, 3311, 3599, 3899, 4211, 4535, 4871, 5219, 5579, 5951, 6335, 6731, 7139, 7559, 7991, 8435, 8891, 9359, 9839, 10331, 10835, 11351, 11879, 12419
Offset: 0

Views

Author

Jacob Landon (jacoblandon(AT)aol.com), May 09 2009

Keywords

Comments

Star numbers A003154 minus 2.
What A163433 does for a triangle, this sequence is doing for a square but giving one-half the results. Take a square with vertices n, n+1, n+2, and n+3 and find the sum of the four products of each four vertices times the sum of the other three; at n you have n((n+1)+(n+2)+(n+3)) and so on for the other three vertices. The result of all four is 12*n^2 + 36*n + 22; half this is 6*n^2 + 18*n + 11 and gives the numbers in this sequence starting with n = 0. - J. M. Bergot, May 23 2012
Multiplying a(n) by 16 gives the sum of the convolution with itself of each of the 24 permutations of four consecutive numbers. - J. M. Bergot, May 15 2017

Crossrefs

Programs

  • Magma
    [6*n*(n-1)-1: n in [0..50]]; // Vincenzo Librandi, May 16 2017
    
  • Mathematica
    Table[6n(n-1)-1,{n,0,50}] (* or *) LinearRecurrence[{3,-3,1},{-1,-1,11},50] (* Harvey P. Dale, Nov 14 2011 *)
    CoefficientList[Series[(1 - 2 x - 11 x^2) / (x - 1)^3, {x, 0, 50}], x] (* Vincenzo Librandi, May 16 2017 *)
  • PARI
    a(n)=6*n*(n-1)-1 \\ Charles R Greathouse IV, Jun 16 2017

Formula

a(n) = A003154(n) - 2.
G.f.: (1-2*x-11*x^2)/(x-1)^3. - R. J. Mathar, May 11 2009 (adapted by Vincenzo Librandi, May 16 2017).
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3), with a(0)=-1, a(1)=-1, a(2)=11. - Harvey P. Dale, Nov 14 2011
a(n) = (n-2)*(n-1 + n + n+1) + (n-1)*(n + n+1) + n*(n+1), which is applying A000914 to four consecutive numbers. - J. M. Bergot, May 15 2017
Sum_{n>=1} 1/a(n) = tan(sqrt(5/3)*Pi/2)*Pi/(2*sqrt(15)). Amiram Eldar, Aug 20 2022
E.g.f.: exp(x)*(6*x^2 - 1). - Elmo R. Oliveira, Jan 16 2025

Extensions

Edited and extended by R. J. Mathar, May 11 2009
Entries rechecked by N. J. A. Sloane, Jul 18 2009

A110426 The r-th term of the n-th row of the following array contains the sum of r successively decreasing integers beginning from n, 0 < r <= n (see Example).

Original entry on oeis.org

1, 3, 3, -5, -30, -84, -182, -342, -585, -935, -1419, -2067, -2912, -3990, -5340, -7004, -9027, -11457, -14345, -17745, -21714, -26312, -31602, -37650, -44525, -52299, -61047, -70847, -81780, -93930, -107384, -122232, -138567, -156485, -176085, -197469, -220742, -246012, -273390, -302990
Offset: 1

Views

Author

Amarnath Murthy, Aug 01 2005

Keywords

Examples

			The r-th term of the n-th row of the following array contains the sum of r successively decreasing integers beginning from n, 0 < r <=n.
E.g., the row corresponding to 4 contains 4, (3+2),{(1) +(0)+(-1)}, {(-2)+(-3)+(-4)+(-5)} ----> 4,5,0,-14
  1
  2 1
  3 3 -3
  4 5 0 -14
  5 7 3 -10 -35
  6 9 6 -6 -30 -69
  ...
Sequence contains the row sums.
		

Crossrefs

Programs

  • Mathematica
    A110426[n_] := n*(n + 1)*(2 - (n - 3)*n)/8; Array[A110426, 50] (* or *)
    LinearRecurrence[{5, -10, 10, -5, 1}, {1, 3, 3, -5, -30}, 50] (* Paolo Xausa, Aug 26 2025 *)
  • PARI
    Vec(x*(1 - 2*x - 2*x^2)/(1 - x)^5 + O(x^50)) \\ Colin Barker, May 27 2017

Formula

a(n) = Sum_{i=(2-n)*(n+1)/2..n} i = (-n^4 + 2*n^3 + 5*n^2 + 2*n)/8. - Theresa Guinard, Nov 15 2013
a(n) = A000330(n) - A000914(n-1). - J. M. Bergot, May 27 2017
From Colin Barker, May 27 2017: (Start)
G.f.: x*(1 - 2*x - 2*x^2)/(1 - x)^5.
a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>5. (End)
E.g.f.: -x*(-8 - 4*x + 4*x^2 + x^3)*exp(x)/8. - Elmo R. Oliveira, Aug 24 2025

Extensions

More terms from Joshua Zucker, May 10 2006

A259460 From higher-order arithmetic progressions.

Original entry on oeis.org

4, 220, 10500, 535500, 30870000, 2044828800, 156029328000, 13673998800000, 1369285948800000, 155756276676000000, 20005336176265440000, 2884501462544301600000, 464334381775424160000000, 83021688624014300160000000, 16408769917253890176000000000, 3569104362241728159962112000000, 850861011640079911341911040000000
Offset: 0

Views

Author

N. J. A. Sloane, Jun 30 2015

Keywords

Comments

The expression "2 over n!" in the article is A006472(n+1). It is used in C_1, C_2, C_3 (A259459, A259460, A378234) on page 13. A_2 is A000914. - Georg Fischer, Dec 06 2024

Crossrefs

Programs

  • Maple
    rV := proc(n,a,d)
        n*(n+1)/2*a+(n-1)*n*(n+1)/6*d;
    end proc:
    A259460 := proc(n)
        mul(rV(i,a,d),i=1..n+2) ;
        coeftayl(%,d=0,2) ;
        coeftayl(%,a=0,n) ;
    end proc:
    seq(A259460(n),n=1..18) ; # R. J. Mathar, Jul 14 2015
  • Mathematica
    rV[n_, a_, d_] := n (n + 1)/2*a + (n - 1) n (n + 1)/6*d;
    A259460[n_] :=
       Product[rV[i, a, d], {i, 1, n + 3}] //
       SeriesCoefficient[#, {d, 0, 2}] & //
       SeriesCoefficient[#, {a, 0, n + 1}] & ;
    Table[A259460[n], {n, 0, 16}] (* Jean-François Alcover, Apr 27 2023, after R. J. Mathar *)

Formula

From Georg Fischer, Dec 06 2024: (Start)
a(n) = (n+4)!*(n+3)!/2^(n+3)/9 * (n+2)*(n+1)*(n+3)*(3*n+8)/24.
D-finite with recurrence: 2*n*(3*n+5)*a(n) - (n+3)^2*(n+4)*(3*n+8)*a(n-1) = 0. (End)

Extensions

Typos in data corrected by Jean-François Alcover, Apr 27 2023

A259463 From higher-order arithmetic progressions.

Original entry on oeis.org

5, 550, 61250, 8330000, 1440600000, 318084480000, 88994505600000, 31196975040000000, 13537335651840000000, 7186069008518400000000, 4614893517270516480000000, 3548831033950800998400000000, 3237226357799023349760000000000, 3472842105575052965314560000000000
Offset: 0

Views

Author

N. J. A. Sloane, Jun 30 2015

Keywords

Comments

"3 over n!" on page 15 in the Dienger article is A087047; A_2 is A000914. - Georg Fischer, Dec 16 2024

Crossrefs

Programs

  • Maple
    rXI := proc(n, a, d)
            n*(n+1)*(n+2)/6*a+(n+2)*(n+1)*n*(n-1)/24*d;
    end proc:
    A259463 := proc(n)
            mul(rXI(i, a, d), i=1..n+2) ;
            coeftayl(%, d=0, 2) ;
            coeftayl(%, a=0, n) ;
    end proc:
    seq(A259463(n), n=1..25) ; # R. J. Mathar, Jul 15 2015
  • Mathematica
    rXI[n_, a_, d_] := n(n+1)(n+2)/6 a + (n+2)(n+1)n(n-1)/24 d;
    A259463[n_] := Product[rXI[i, a, d], {i, 1, n+3}]//
       SeriesCoefficient[#, {d, 0, 2}]&//
       SeriesCoefficient[#, {a, 0, n+1}]&;
    Table[A259463[n], {n, 0, 13}] (* Jean-François Alcover, May 02 2023, after R. J. Mathar *)

Formula

D-finite with recurrence: -6*n*(3*n+5)*a(n) +(n+5)*(n+4)*(3*n+8)*(n+3)^2*a(n-1)=0. - R. J. Mathar, Jul 15 2015
a(n) = 2^(-n-4)*3^(-n-3)*(n+3)!*(n+4)!*(n+5)!*(n+2)*(n+1)*(n+3)*(3*n+8)/384. - Georg Fischer, Dec 16 2024

Extensions

Corrected by Jean-François Alcover, May 02 2023

A191685 Eighth diagonal a(n) = s(n,n-7) of the unsigned Stirling numbers of the first kind with n>7.

Original entry on oeis.org

5040, 109584, 1172700, 8409500, 45995730, 206070150, 790943153, 2681453775, 8207628000, 23057159840, 60202693980, 147560703732, 342252511900, 756111184500, 1599718388730, 3256091103430, 6400590336096, 12191224980000, 22563937825000, 40681506808800
Offset: 8

Views

Author

Paul Weisenhorn, Jun 11 2011

Keywords

Comments

The Maple programs under I generate the sequence. The Maple program under II generates explicit formulas for a(n+1) = s(n+1,n+1-c) with c>=1 and n>=c.

Examples

			c=1; a(n+1) = binomial(n+1,2)
c=2; a(n+1) = binomial(n+1,3)*(2+3*n)/4
c=3; a(n+1) = binomial(n+1,4)*(n+n^2)/2
c=4; a(n+1) = binomial(n+1,5)*(-8-10*n+15*n^2 +15*n^3)/48
c=5; a(n+1) = binomial(n+1,6)*(-6*n-7*n^2+2*n^3+ 3*n^4)/16
c=6; a(n+1) = binomial(n+1,7)*(96+140*n-224*n^2-315*n^3+63*n^5)/576
c=7; a(n+1) = binomial(n+1,8)*(80*n+114*n^2-23*n^3-75*n^4-9*n^5+9*n^6)/144
c=8; a(n+1) = binomial(n+1,9)*(-1152-1936*n+2820*n^2+
  5320*n^3+735*n^4-1575*n^5-315*n^6+135*n^7)/3840
c=9; a(n+1) = binomial(n+1,10)*(-1008*n-1676*n^2 +100*n^3+1295*n^4+392*n^5-210*n^6-60*n^7 +15*n^8)/768
		

References

  • K. Seidel, Variation der Binomialkoeffizienten, Bild
  • der Wissenschaft, 6 (1980), pp. 127-128.

Crossrefs

Cf. A130534, A000012 (c=0; 1st diagonal), A000217 (c=1; 2nd diagonal), A000914 (c=2; 3rd diagonal), A001303 (c=3; 4th diagonal), A000915 (c=4; 5th diagonal), A053567 (c=5; 6th diagonal), A112002 (c=6; 7th diagonal), A191685 (c=7; 8th diagonal).

Programs

  • Maple
    I: programs generate the sequence:
    with(combinat): c:=7; a:= proc(n) a(n):=abs(stirling1(n,n-c)); end: seq(a(n), n=c+1..28);
    for n from 7 to 27 do a(n+1) := binomial(n+1,8)*(80*n+ 114*n^2- 23*n^3- 75*n^4- 9*n^5+ 9*n^6)/144 end do: seq(a(n),n=8..28);
    II: program generates explicit formulas for a(n+1) =  s(n+1,n+1-c):
    k[1,0]:=1: v:=1:
    for c from 2 to 10 do
      c1:=c-1: c2:=c-2: p0:=0:
      for j from 0 to c2 do p0:=p0+k[c1,j]*m^j: end do:
      f:=expand(2*c*(m+1)*p0/v):
      p1:=0: p2:=0:
      for j from 0 to c1 do
        p1:=p1+k[c,j]*(m+1)^j:
        p2:=p2+k[c,j]*m^j:
      end do:
      g:=collect((m+2)*p1-(m-c1)*p2-f,m):
      kh[0]:=rem(g,m,m): Mk:=[kh[0]]: Mv:=[k[c,0]]:
      for j from 1 to c1 do
        kh[j]:=coeff(g,m^j):
        Mk:=[op(Mk),kh[j]]: Mv:=[k[c,j],op(Mv)]:
      end do:
      sol:=solve(Mk,Mv):
      v:=1:
      for j from 1 to c do
        k[c,c-j]:=eval(k[c,c-j],sol[1,j]):
        nen[j]:=denom(k[c,c-j]):
        v:=ilcm(v,nen[j]):
      end do:
      for j from 0 to c1 do k[c,j]:=k[c,j]*v:
        printf("%8d",k[c,j]): end do:
      p3:=0:
      for j from 0 to c1 do p3:=p3+k[c,j]*n^j: end do:
      s[n+1,n+1-c]:=binomial(n+1,c+1)*(c+1)*p3/(2^c*k[c,c1]):
    end do:
    for c from 2 to 10 do print("%a\n",s[n+1,n+1-c]):
    end do:

Formula

a(n+1) = A130534(T(n,n-7)) = s(n+1,n+1-7)
a(n+1) = binomial(n+1,8)*(80*n+114*n^2-23*n^3-75*n^4-9*n^5+9*n^6)/144

A253171 a(n) = number of permutations of (1,2,...,n) producible by an ordered triple of distinct transpositions.

Original entry on oeis.org

3, 12, 60, 240, 756, 1988, 4572, 9495, 18205, 32736, 55848, 91182, 143430, 218520, 323816, 468333, 662967, 920740, 1257060, 1689996, 2240568, 2933052, 3795300, 4859075, 6160401, 7739928, 9643312, 11921610, 14631690, 17836656, 21606288, 26017497, 31154795
Offset: 3

Views

Author

Andrew Woods, Dec 28 2014

Keywords

Examples

			For n=4, the 12 permutations are 0132, 0213, 0321, 1023, 1230, 1302, 2031, 2103, 2310, 3012, 3120, and 3201. For example, 0123 is permuted into 0132 by ((b,d),(c,d), (b,c)).
		

Crossrefs

Cf. A000914, for two transpositions.

Programs

  • PARI
    Vec(-x^3*(x^6-7*x^5+21*x^4-33*x^3+39*x^2-9*x+3)/(x-1)^7 + O(x^100)) \\ Colin Barker, Dec 30 2014

Formula

a(n) = n * (n^5 - 7*n^4 + 17*n^3 - 17*n^2 + 30*n - 24) / 48 for n>=3.
a(n) = C(n,2)*(C(n-2,2)*C(n-4,2)/6 + 1) + 2*C(n,3)*C(n-3,2) + 6*C(n,4) for n>=3.
G.f.: -x^3*(x^6-7*x^5+21*x^4-33*x^3+39*x^2-9*x+3) / (x-1)^7. - Colin Barker, Dec 30 2014

Extensions

More terms from Colin Barker, Dec 30 2014

A259457 From higher-order arithmetic progressions.

Original entry on oeis.org

3, 66, 1050, 15300, 220500, 3245760, 49533120, 789264000, 13172544000, 230519520000, 4229703878400, 81315551116800, 1636227552960000, 34417989365760000, 755835784704000000, 17305616126582784000, 412559358036553728000, 10227311816872550400000, 263309943217447526400000, 7032029553158658048000000
Offset: 0

Views

Author

N. J. A. Sloane, Jun 30 2015

Keywords

Crossrefs

Programs

  • Maple
    rX := proc(n, a, d)
            n*a+(n-1)*n/2*d;
    end proc:
    A259457 := proc(n)
            mul(rX(i, a, d), i=1..n+2) ;
            coeftayl(%, d=0, 2) ;
            coeftayl(%, a=0, n) ;
    end proc:
    seq(A259457(n), n=1..25) ; # R. J. Mathar, Jul 15 2015
  • Mathematica
    rX[n_, a_, d_] := n*a + (n-1)*n/2*d;
    A259457[n_] :=
       Product[rX[i, a, d], {i, 1, n+3}]//
       SeriesCoefficient[#, {d, 0, 2}]&//
       SeriesCoefficient[#, {a, 0, n+1}]&;
    Table[A259457[n], {n, 0, 17}] (* Jean-François Alcover, Apr 27 2023, after R. J. Mathar *)

Formula

Conjecture: 3*n*a(n) +(-3*n^2-19*n-44)*a(n-1) -2*(n+2)^2*a(n-2)=0. - R. J. Mathar, Jul 15 2015
From Georg Fischer, Dec 06 2024: (Start)
a(n) = (n+3)!*(n+2)*(n+1)*(n+3)*(3*n+8)/96.
D-finite with recurrence: -n*(3*n+5)*a(n) + (n+3)^2*(3*n+8)*a(n-1) = 0. (End)

A024169 Integer part of ((2nd elementary symmetric function of 1,2,...,n)/(1+2+...+n)).

Original entry on oeis.org

0, 0, 1, 3, 5, 8, 11, 15, 19, 24, 29, 34, 41, 47, 54, 62, 70, 79, 88, 98, 108, 119, 130, 141, 154, 166, 179, 193, 207, 222, 237, 253, 269, 286, 303, 320, 339, 357, 376, 396, 416, 437, 458, 480, 502
Offset: 1

Views

Author

Keywords

Programs

  • GAP
    List([1..50],n->Int((1/12)*(n-1)*(3*n+2))); # Muniru A Asiru, May 19 2018
  • Maple
    seq(floor((1/12)*(n-1)*(3*n+2)),n=1..50); # Muniru A Asiru, May 19 2018
  • Mathematica
    Table[Floor[1/12 (n - 1) (3 n + 2)], {n, 45}] (* Ivan Neretin, May 19 2018 *)

Formula

From R. J. Mathar, Sep 15 2009: (Start)
a(n) = floor( A000914(n-1)/A000217(n)).
G.f.: x^3*(-1-x-x^5-2*x^7+x^4+x^8)/((x^2+1) * (1+x+x^2) * (x^4-x^2+1) * (x-1)^3). (End)
a(n) = floor((1/12)*(n - 1)*(3*n + 2)). - Ivan Neretin, May 19 2018
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