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 1-3 of 3 results.

A026045 a(n) = (d(n)-r(n))/5, where d = A026043 and r is the periodic sequence with fundamental period (0,2,3,0,0).

Original entry on oeis.org

9, 13, 19, 28, 39, 53, 70, 91, 117, 147, 182, 222, 268, 321, 380, 446, 519, 600, 690, 788, 895, 1011, 1137, 1274, 1421, 1579, 1748, 1929, 2123, 2329, 2548, 2780, 3026, 3287, 3562, 3852, 4157, 4478, 4816, 5170, 5541, 5929, 6335, 6760, 7203, 7665, 8146, 8647, 9169, 9711, 10274, 10858, 11464
Offset: 1

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Author

Keywords

Crossrefs

A152857 [From Richard Choulet, Dec 14 2008]

Formula

a(n)=(n + 5)*(2*n^2 + 11*n + 54)/30 - (1 + ( - 1/2 - 1/10*5^(1/2))*cos(2*n*Pi/5) + (1/10*(3*(5 - 5^(1/2))^(1/2) + 2*(5 + 5^(1/2))^(1/2))*2^(1/2))*sin(2*n*Pi/5) + (1/10*5^(1/2) - 1/2)*cos(4*n*Pi/5) + (1/10*(2*(5 - 5^(1/2))^(1/2) - 3*(5 + 5^(1/2))^(1/2))*2^(1/2))*sin(4*n*Pi/5))/5 [From Richard Choulet, Dec 14 2008]
G.f. x*( 9-14*x+7*x^2+x^3-x^4-8*x^5-6*x^7+14*x^6 ) / ( (x^4+x^3+x^2+x+1)*(x-1)^4 ). - R. J. Mathar, Jun 22 2013

A026044 a(n) = (d(n)-r(n))/2, where d = A026043 and r is the periodic sequence with fundamental period (1,1,0,0).

Original entry on oeis.org

22, 33, 49, 70, 97, 132, 176, 229, 292, 367, 455, 556, 671, 802, 950, 1115, 1298, 1501, 1725, 1970, 2237, 2528, 2844, 3185, 3552, 3947, 4371, 4824, 5307, 5822, 6370, 6951, 7566, 8217, 8905, 9630, 10393, 11196, 12040, 12925, 13852, 14823, 15839, 16900, 18007, 19162, 20366, 21619, 22922, 24277
Offset: 5

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Author

Keywords

Programs

  • Mathematica
    LinearRecurrence[{4,-7,8,-7,4,-1},{22,33,49,70,97,132},60] (* Harvey P. Dale, Apr 27 2019 *)

Formula

a(n)=(n + 5)*(2*n^2 + 11*n + 54)/12 - 1/4 - (1/4)*cos(Pi*n/2) - (1/4)*sin(Pi*n/2) [From Richard Choulet, Dec 13 2008]
G.f. x^5*( 22-55*x+71*x^2-71*x^3+50*x^4-15*x^5 ) / ( (x^2+1)*(x-1)^4 ). - R. J. Mathar, Jun 22 2013

A094414 Triangle T read by rows: dot product <1,2,...,r> * .

Original entry on oeis.org

1, 5, 4, 14, 11, 11, 30, 24, 22, 24, 55, 45, 40, 40, 45, 91, 76, 67, 64, 67, 76, 140, 119, 105, 98, 98, 105, 119, 204, 176, 156, 144, 140, 144, 156, 176, 285, 249, 222, 204, 195, 195, 204, 222, 249, 385, 340, 305, 280, 265, 260, 265, 280, 305, 340, 506, 451, 407, 374, 352, 341, 341, 352, 374, 407, 451
Offset: 0

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Author

Ralf Stephan, May 02 2004

Keywords

Comments

Offset for r (the rows) is 1, for s (the columns) it is 0.

Examples

			Triangle begins as:
   1;
   5,  4;
  14, 11, 11;
  30, 24, 22, 24;
  55, 45, 40, 40, 45;
  91, 76, 67, 64, 67, 76;
		

Crossrefs

Row sums are A000537.
See also A094415, A088003.

Programs

  • GAP
    Flat(List([0..12], n-> List([0..n-1], k-> n*((n+1)*(2*n+1) -3*k*(n-k))/6 ))); # G. C. Greubel, Oct 30 2019
  • Magma
    [n*((n+1)*(2*n+1) -3*k*(n-k))/6: k in [0..n-1], n in [0..12]]; // G. C. Greubel, Oct 30 2019
    
  • Maple
    T:=proc(r,s) if s>=r then 0 else r*(2*r^2+3*r+1-3*r*s+3*s^2)/6 fi end: for r from 1 to 11 do seq(T(r,s),s=0..r-1) od; # yields sequence in triangular form # Emeric Deutsch, Nov 27 2006
  • Mathematica
    Table[n*((n+1)*(2*n+1) -3*k*(n-k))/6, {n,0,12}, {k,0,n-1}]//Flatten (* G. C. Greubel, Oct 30 2019 *)
  • PARI
    T(n,k) = n*((n+1)*(2*n+1) -3*k*(n-k))/6;
    for(n=0,12, for(k=0,n-1, print1(T(n,k), ", "))) \\ G. C. Greubel, Oct 30 2019
    
  • Sage
    [[n*((n+1)*(2*n+1) -3*k*(n-k))/6 for k in (0..n-1)] for n in (0..12)] # G. C. Greubel, Oct 30 2019
    

Formula

T(r, s) = r*(2*r^2 + 3*r - 3*r*s + 1 + 3*s^2)/6, r >= 1, 0 <= s <= r-1.

Extensions

More terms from G. C. Greubel, Oct 30 2019
Showing 1-3 of 3 results.