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.

A316466 a(n) = 2*n*(7*n - 3).

Original entry on oeis.org

0, 8, 44, 108, 200, 320, 468, 644, 848, 1080, 1340, 1628, 1944, 2288, 2660, 3060, 3488, 3944, 4428, 4940, 5480, 6048, 6644, 7268, 7920, 8600, 9308, 10044, 10808, 11600, 12420, 13268, 14144, 15048, 15980, 16940, 17928, 18944, 19988, 21060, 22160, 23288, 24444, 25628, 26840
Offset: 0

Views

Author

Bruno Berselli, Jul 04 2018

Keywords

Comments

This is the case k = 9 of Sum_{i = 2..k} P(i,n) = (k - 1)*n*((k - 2)*n - (k - 6))/4, where P(k,n) = n*((k - 2)*n - (k - 4))/2 (see Crossrefs for similar sequences and "Square array in A139600" in Links section).
14*x + 9 is a square for x = a(n) or x = a(-n).

Crossrefs

Similar sequences (see the first comment): A000096 (k = 3), A045943 (k = 4), A049451 (k = 5), A033429 (k = 6), A167469 (k = 7), A152744 (k = 8), this sequence (k = 9), A152994 (k = 10).

Programs

  • GAP
    List([0..50], n -> 2*n*(7*n-3));
    
  • Julia
    [2*n*(7*n-3) for n in 0:50] |> println
  • Magma
    [2*n*(7*n-3): n in [0..50]];
    
  • Mathematica
    Table[2 n (7 n - 3), {n, 0, 50}]
    LinearRecurrence[{3,-3,1},{0,8,44},50] (* Harvey P. Dale, Jan 24 2021 *)
  • Maxima
    makelist(2*n*(7*n-3), n, 0, 50);
    
  • PARI
    vector(50, n, n--; 2*n*(7*n-3))
    
  • PARI
    concat(0, Vec(4*x*(2 + 5*x)/(1 - x)^3 + O(x^40))) \\ Colin Barker, Jul 05 2018
    
  • Python
    [2*n*(7*n-3) for n in range(50)]
    
  • Sage
    [2*n*(7*n-3) for n in (0..50)]
    

Formula

O.g.f.: 4*x*(2 + 5*x)/(1 - x)^3.
E.g.f.: 2*x*(4 + 7*x)*exp(x).
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3).
a(n) = 4*A218471(n).

A139609 a(n) = 36*n + 9.

Original entry on oeis.org

9, 45, 81, 117, 153, 189, 225, 261, 297, 333, 369, 405, 441, 477, 513, 549, 585, 621, 657, 693, 729, 765, 801, 837, 873, 909, 945, 981, 1017, 1053, 1089, 1125, 1161, 1197, 1233, 1269, 1305, 1341, 1377, 1413, 1449, 1485, 1521, 1557, 1593, 1629, 1665, 1701
Offset: 0

Views

Author

Omar E. Pol, Apr 27 2008

Keywords

Comments

Numbers of the 9th column of positive numbers in the square array of nonnegative and polygonal numbers A139600.

Crossrefs

Programs

Formula

a(n) = A057145(n+2,9).
G.f.: 9*(1+3*x)/(x-1)^2. - R. J. Mathar, Jul 28 2016
From Elmo R. Oliveira, Apr 16 2024: (Start)
E.g.f.: 9*exp(x)*(1 + 4*x).
a(n) = 2*a(n-1) - a(n-2) for n >= 2.
a(n) = 9*A016813(n) = A044102(n) + 9 = A152994(n+1) - A152994(n). (End)

A144560 Ten times hexagonal numbers: 10*n*(2*n-1).

Original entry on oeis.org

0, 10, 60, 150, 280, 450, 660, 910, 1200, 1530, 1900, 2310, 2760, 3250, 3780, 4350, 4960, 5610, 6300, 7030, 7800, 8610, 9460, 10350, 11280, 12250, 13260, 14310, 15400, 16530, 17700, 18910, 20160, 21450, 22780, 24150, 25560, 27010
Offset: 0

Views

Author

Omar E. Pol, Jan 01 2009

Keywords

Comments

Sequence found by reading the line from 0, in the direction 0, 10,..., in the square spiral whose vertices are the generalized dodecagonal numbers A195162. - Omar E. Pol, Sep 18 2011

Crossrefs

Programs

Formula

a(n) = 20*n^2 - 10*n = 10*A000384(n) = 5*A002939(n) = 2*A152745(n).
a(n) = a(n-1) +40*n -30 (with a(0)=0). - Vincenzo Librandi, Dec 14 2010
From G. C. Greubel, May 30 2024: (Start)
G.f.: 10*x*(1 + 3*x)/(1-x)^3.
E.g.f.: 10*x*(1 + 2*x)*exp(x). (End)
Showing 1-3 of 3 results.