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.

Previous Showing 11-19 of 19 results.

A259464 From higher-order arithmetic progressions.

Original entry on oeis.org

75, 21875, 5512500, 1512630000, 484041600000, 184834742400000, 84715923600000000, 46534591303200000000, 30489464221856640000000, 23681690417572387200000000, 21660852835272876825600000000, 23175597788788462617600000000000, 28817200450516396946227200000000000
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_3 is A001303. - 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:
    A259464 := proc(n)
            mul(rXI(i, a, d), i=1..n+3) ;
            coeftayl(%, d=0, 3) ;
            coeftayl(%, a=0, n) ;
    end proc:
    seq(A259464(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;
    A259464[n_] :=
       Product[rXI[i, a, d], {i, 1, n+4}]//
       SeriesCoefficient[#, {d, 0, 3}]&//
       SeriesCoefficient[#, {a, 0, n+1}]&;
    Table[A259464[n], {n, 0, 12}] (* Jean-François Alcover, Apr 26 2023, after R. J. Mathar *)

Formula

D-finite with recurrence: -6*n*(n+2)*a(n) +(n+6)*(n+5)*(n+4)^3*a(n-1)=0. - R. J. Mathar, Jul 15 2015
a(n) = 2^(-n-5)*3^(-n-4)*(n+4)!*(n+5)!*(n+6)!*(n+4)^2*(n+3)^2*(n+2)*(n+1)/3072. - Georg Fischer, Dec 16 2024

A378234 From higher-order arithmetic progressions: Corrected version of A259461.

Original entry on oeis.org

40, 5000, 472500, 43218000, 4148928000, 432081216000, 49509306000000, 6275893932000000, 881135508052800000, 136878615942868800000, 23474682634201999200000, 4432282735129048800000000, 918537831584839065600000000, 208281986149676045967360000000, 51516317681413623440962560000000
Offset: 0

Views

Author

Georg Fischer, Dec 16 2024

Keywords

Comments

Only the first 5 terms of A259461 are correct. - R. J. Mathar, Jul 14 2015
"2 over n!" on page 13 in the Dienger article is A006472; A_3 is A001303.

Crossrefs

Programs

  • Maple
    rV := proc(n,a,d)
        n*(n+1)/2*a+(n-1)*n*(n+1)/6*d;
    end proc:
    A259461 := proc(n)
        mul(rV(i,a,d),i=1..n+3) ;
        coeftayl(%,d=0,3) ;
        coeftayl(%,a=0,n) ;
    end proc:
    seq(A259461(n),n=1..5) ; # R. J. Mathar, Jul 14 2015

Formula

D-finite with recurrence: -2*n*(n+2)*a(n) + (n+4)^3*(n+5)*a(n-1) = 0.
a(n) = (n+5)!*(n+4)!^3 / (1296*2^(n+4)*n!^2*(n+2)*(n+1)).

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

A352980 a(n) = Sum_{1 <= i < j < k <= n} (k*j*i)^3.

Original entry on oeis.org

0, 0, 0, 216, 16280, 335655, 3587535, 25421200, 135459216, 584760870, 2145870870, 6918983280, 20073184560, 53334782501, 131555523645, 304453955520, 666698215360, 1390977293580, 2780695001196, 5351537889480, 9954554649480, 17957698726275
Offset: 0

Views

Author

Roudy El Haddad, Apr 13 2022

Keywords

Comments

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

Crossrefs

Cf. A352979 (for nondistinct cubes).
Cf. A001303 (for power 1), A000597 (for squares).
Cf. A000578 (cubes), A000537 (sum of first n cubes), A347107 (order 2).

Programs

  • PARI
    {a(n) = n^2 * (n + 1)^2 * (n - 1) * (n - 2) * (35*n^6 + 5*n^5 - 237*n^4 - 77*n^3 + 502*n^2 + 148*n -336)/13440};
    
  • Python
    def A352980(n): return n**2*(n*(n*(n*(n*(n*(n*(n*(n*(n*(35*n - 30) - 347) + 180) + 1365) - 350) - 2541) + 240) + 2160) - 40) - 672)//13440 # Chai Wah Wu, May 15 2022

Formula

a(n) = Sum_{k=3..n} Sum_{j=2..k-1} Sum_{i=1..j-1} k^3*j^3*i^3.
a(n) = n^2 * (n + 1)^2 * (n - 1) * (n - 2) * (35*n^6 + 5*n^5 - 237*n^4 - 77*n^3 + 502*n^2 + 148*n -336)/13440.
a(n) = binomial(n+1,4)*binomial(n+1,2)*(35*n^6 + 5*n^5 - 237*n^4 - 77*n^3 + 502*n^2 + 148*n -336)/280.

A024172 Integer part of ((3rd elementary symmetric function of 1,2,..,n)/(2nd elementary symmetric function of 1,2,...,n)).

Original entry on oeis.org

0, 0, 1, 2, 4, 6, 8, 10, 13, 16, 20, 24, 28, 33, 38, 43, 48, 54, 60, 67, 74, 81, 89, 97, 105, 113, 122, 131, 141, 151, 161, 172, 183, 194, 205, 217, 229, 242, 255, 268, 282, 296, 310, 324
Offset: 2

Views

Author

Keywords

Examples

			a(3) = floor(6/11) = 0; a(4) = floor(50/35) = 1. - _R. J. Mathar_, Sep 15 2009
		

Programs

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

Formula

a(n) = floor( A001303(n-2)/A000914(n-1) ). - R. J. Mathar, Sep 15 2009
Empirical g.f.: x^4*(x^4-x^3+x^2-x+1)*(x^5-x^3-x^2-x-1) / ((x-1)^3*(x^2+x+1)*(x^6+x^3+1)). - Colin Barker, Aug 16 2014
a(n) = floor((1/2)*(n - 2)*n*(n + 1)/(3*n + 2)).

Extensions

Offset set to 2 by R. J. Mathar, Sep 15 2009

A024174 a(n) is floor((4th elementary symmetric function of 1,2,..,n)/(3rd elementary symmetric function of 1,2,...,n)).

Original entry on oeis.org

0, 0, 1, 2, 3, 4, 6, 8, 10, 13, 16, 19, 22, 25, 29, 33, 37, 42, 47, 52, 57, 62, 68, 74, 80, 87, 94, 101, 108, 115, 123, 131, 139, 148, 157, 166, 175, 184, 194, 204, 214, 225, 236, 247, 258, 269, 281, 293, 305, 318, 331, 344, 357, 370, 384, 398, 412, 427, 442
Offset: 3

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Author

Keywords

Examples

			G.f. = x^5 + 2*x^6 + 3*x^7 + 4*x^8 + 6*x^9 + 8*x^10 + 10*x^11 + 13*x^12 + ...
		

Crossrefs

Programs

  • Mathematica
    Table[Floor[(n - 3) (15 n^3 + 15 n^2 - 10 n - 8)/(120 n (n + 1))], {n, 3, 45}] (* Ivan Neretin, Nov 25 2016 *)
    Insert[Table[Floor[1/8 (-2 - 3 n + n^2)], {n, 4, 45}], 0, 1] (* Ralf Steiner, Oct 27 2021 *)
  • PARI
    {a(n) = if( n<4, 0, (n-3) * (15*n^3 + 15*n^2 - 10*n - 8) \ (120 * n * (n+1)))}; /* Michael Somos, Nov 25 2016 */

Formula

Empirical g.f.: x^5*(x^7-2*x^6+2*x^5-2*x^4+x^3-x^2+x-1) / ((x-1)^3*(x^2+1)*(x^4+1)). - Colin Barker, Aug 16 2014
a(n) = floor( A000915(n-3)/A001303(n-2) ). - R. J. Mathar, Sep 23 2016
a(n) = floor((n - 3)*(15n^3 + 15n^2 - 10n - 8)/(120*n*(n + 1))). - Ivan Neretin, Nov 25 2016
a(n) = floor((A000217(n-2)/2 - 1)/2) = floor((n^2 - 3*n - 2)/8), n >= 4. - Ralf Steiner, Oct 25 2021

Extensions

Offset set to 3 by R. J. Mathar, Sep 23 2016

A027919 a(n) = least k such that 2nd elementary symmetric function of {1,2,...,k+1} >= 3rd elementary symmetric function of {1,2,...,n}.

Original entry on oeis.org

2, 4, 6, 8, 11, 13, 16, 19, 22, 25, 29, 32, 36, 39, 43, 47, 51, 56, 60, 64, 69, 74, 78, 83, 88, 93, 98, 103, 109, 114, 119, 125, 131, 136, 142, 148, 154, 160, 166, 172, 178, 185, 191, 198, 204, 211, 217, 224, 231, 238, 245, 252, 259, 266
Offset: 3

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Author

Keywords

Crossrefs

Programs

  • Maple
    SymmPolyn := proc(L::list,n::integer)
        local c,a,sel;
        a :=0 ;
        sel := combinat[choose](nops(L),n) ;
        for c in sel do
            a := a+mul(L[e],e=c) ;
        end do:
        a;
    end proc:
    A027919 := proc(n)
         local k,i;
         [seq(i,i=1..n)] ;
        e3 := SymmPolyn(%,3) ;
        for k from 1 do
            [seq(i,i=1..k+1)] ;
            if SymmPolyn(%,2) >= e3 then
                return k;
            end if;
        end do:
    end proc: # R. J. Mathar, Sep 23 2016

Formula

a(n) = min{k: A000914(k) >= A001303(n-2)}. - Sean A. Irvine, Dec 10 2019

Extensions

Definition modified by R. J. Mathar, Sep 23 2016

A259458 From higher-order arithmetic progressions.

Original entry on oeis.org

18, 750, 20250, 463050, 9878400, 205752960, 4286520000, 90561240000, 1956122784000, 43410118752000, 992644715462400, 23427803599200000, 571192163942400000, 14391113340764160000, 374682915193466880000, 10078235746321526784000, 279950992953375744000000, 8026706333564126208000000
Offset: 0

Views

Author

N. J. A. Sloane, Jun 30 2015

Keywords

Comments

A_2 in page 12 of the article is A001303. - Georg Fischer, Dec 06 2024

Crossrefs

Programs

  • Maple
    rX := proc(n, a, d)
            n*a+(n-1)*n/2*d;
    end proc:
    A259458 := proc(n)
            mul(rX(i, a, d), i=1..n+3) ;
            coeftayl(%, d=0, 3) ;
            coeftayl(%, a=0, n) ;
    end proc:
    seq(A259458(n), n=1..25) ; # R. J. Mathar, Jul 15 2015
  • Mathematica
    rX[n_, a_, d_] := n*a + (n-1)*n/2*d;
    A259458[n_] :=
       Product[rX[i, a, d], {i, 1, n+4}] //
       SeriesCoefficient[#, {d, 0, 3}]& //
       SeriesCoefficient[#, {a, 0, n+1}]&;
    Table[A259458[n], {n, 0, 16}] (* Jean-François Alcover, Apr 27 2023, after R. J. Mathar *)

Formula

D-finite with recurrence: -n*(n+2)*a(n) +(n+4)^3*a(n-1)=0. - R. J. Mathar, Jul 15 2015
Conjectured g.f.: 18*3F1(5,5,5;3;x). - R. J. Mathar, Aug 09 2015
a(n) = (n+4)!*(n+1)*(n+2)*(n+3)^2*(n+4)^2/384. - Georg Fischer, Dec 06 2024

A027917 a(n) = least k such that 1+2+...+k >= E{1,2,...,n}, where E is the 3rd elementary symmetric function.

Original entry on oeis.org

3, 10, 21, 38, 63, 95, 137, 191, 256, 334, 427, 535, 661, 805, 968, 1151, 1357, 1585, 1838, 2117, 2422, 2755, 3117, 3510, 3934, 4392, 4883, 5409, 5973, 6574, 7213, 7894, 8615, 9379, 10187, 11041, 11940, 12887, 13883, 14929, 16026, 17176, 18379, 19637, 20952, 22323, 23754, 25244, 26795, 28408
Offset: 3

Views

Author

Keywords

Formula

a(n) = min{k: A000217(k) >= A001303(n-2)}. - R. J. Mathar, Sep 23 2016
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