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 21-30 of 30 results.

A093050 Exponent of 2 in (3^n-3)*2^(n-1).

Original entry on oeis.org

0, 0, 3, 2, 6, 4, 7, 6, 11, 8, 11, 10, 14, 12, 15, 14, 20, 16, 19, 18, 22, 20, 23, 22, 27, 24, 27, 26, 30, 28, 31, 30, 37, 32, 35, 34, 38, 36, 39, 38, 43, 40, 43, 42, 46, 44, 47, 46, 52, 48, 51, 50, 54, 52, 55, 54, 59, 56, 59, 58, 62, 60, 63, 62, 70, 64, 67, 66, 70
Offset: 0

Views

Author

Ralf Stephan, Mar 16 2004

Keywords

Crossrefs

a(n) is the exponent of 2 in A016129(n-1), A024281(n), A024287(n), A066406(n)/2, A071952(n+3).

Programs

  • PARI
    a(n)=if(n<1,0,if(n%2==0,a(n/2)+2*floor((n+2)/4)+1,n-1))

Formula

Recurrence: a(2n) = a(n) + [(n+1)/2] + 1, a(2n+1) = 2n.
G.f.: Sum_{k>=0} t^2(3+2t+2t^3-t^4)/[(1+t^2)(1-t^2)^2], t=x^2^k.
a(n) = A093051(n) - 1 = A090740(n) + n - 2, for n >= 1. - Amiram Eldar, Sep 14 2024

A165147 a(n) = (3*7^n-3^n)/2.

Original entry on oeis.org

1, 9, 69, 501, 3561, 25089, 176109, 1234221, 8643921, 60520569, 423683349, 2965901541, 20761665081, 145332718449, 1017332217789, 7121335090461, 49849374331041, 348945706410729, 2442620203155429, 17098342196928981
Offset: 0

Views

Author

Klaus Brockhaus, Sep 15 2009

Keywords

Comments

Partial sums are in A016138.
Binomial transform of A016129. Inverse binomial transform of A165148.

Crossrefs

Programs

  • Magma
    [ (3*7^n-3^n)/2: n in [0..19] ];
  • Mathematica
    LinearRecurrence[{10, -21}, {1, 9}, 25] (* Paolo Xausa, Apr 22 2024 *)
    Table[(3*7^n-3^n)/2,{n,0,20}] (* Harvey P. Dale, Aug 05 2025 *)

Formula

a(n) = 10*a(n-1)-21*a(n-2) for n > 1; a(0) = 1, a(1) = 9.
G.f.: (1-x)/((1-3*x)*(1-7*x)).

A165152 a(n) = (3*12^n - 8^n)/2.

Original entry on oeis.org

1, 14, 184, 2336, 29056, 356864, 4347904, 52699136, 636583936, 7672561664, 92339175424, 1110217588736, 13339790934016, 160214930161664, 1923678673567744, 23092940175835136, 277185650854199296, 3326790760203812864, 39925992722073124864, 479147941461896462336
Offset: 0

Views

Author

Klaus Brockhaus, Sep 15 2009

Keywords

Comments

Binomial transform of A165151. Sixth binomial transform of A016129. Tenth binomial transform of A056450.

Crossrefs

Programs

Formula

a(n) = 20*a(n-1) - 96*a(n-2) for n > 1; a(0) = 1, a(1) = 14.
G.f.: (1 - 6*x)/((1 - 8*x)*(1 - 12*x)).
E.g.f.: exp(8*x)*(3*exp(4*x) - 1)/2. - Stefano Spezia, Mar 30 2023

A241275 a(n) = 6*a(n-1) + 5*(2^(n-1)-1) for n > 0, a(0) = 0.

Original entry on oeis.org

0, 0, 5, 45, 305, 1905, 11585, 69825, 419585, 2518785, 15115265, 90696705, 544190465, 3265163265, 19591020545, 117546205185, 705277394945, 4231664697345, 25389988839425, 152339934347265, 914039608705025, 5484237657473025, 32905425955323905, 197432555752914945, 1184595334559432705, 7107572007440482305
Offset: 0

Views

Author

Kival Ngaokrajang, Apr 18 2014

Keywords

Comments

a(n) is the total number of holes in a pentaflake after n iterations. The number of irregular polygon-shaped holes is 5*A016200(n-3), n >= 3. The number of rhombic-shaped holes is 5*A016129(n-2), n >= 2 and equal to the first difference of a(n).

Crossrefs

Programs

  • Maple
    A241275:=n->9*6^(n-2) - 5*2^(n-2) + 1; seq(A241275(n), n=0..40); # Wesley Ivan Hurt, Apr 19 2014
  • Mathematica
    CoefficientList[Series[-5 x^2/((x - 1) (2 x - 1) (6 x - 1)), {x, 0, 40}], x] (* Vincenzo Librandi, Apr 19 2014 *)
    LinearRecurrence[{9,-20,12},{0,0,5},30] (* Harvey P. Dale, Oct 10 2017 *)
  • PARI
    a(n)=if(n<=0, 0, a(n-1)*6+5*(2^(n-1)-1))
           for(n=0, 100, print1(a(n),", "))

Formula

a(n) = 5*(A016129(n-2) + A016200(n-3)) for n >= 3, a(0)=a(1)=0, a(2)=5.
a(n) = 5*A016200(n-2) for n >= 2.
a(n) = 9*6^(n-2) - 5*2^(n-2) + 1.
a(n) = (4-5*2^n+6^n)/4. G.f.: -5*x^2 / ((x-1)*(2*x-1)*(6*x-1)). - Colin Barker, Apr 18 2014

Extensions

Typo in DATA fixed by Colin Barker, Apr 18 2014

A361290 Square array T(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where T(n,k) = Sum_{j=0..floor((n-1)/2)} k^(n-1-j) * binomial(n,2*j+1).

Original entry on oeis.org

0, 0, 1, 0, 1, 0, 0, 1, 2, 0, 0, 1, 4, 4, 0, 0, 1, 6, 14, 8, 0, 0, 1, 8, 30, 48, 16, 0, 0, 1, 10, 52, 144, 164, 32, 0, 0, 1, 12, 80, 320, 684, 560, 64, 0, 0, 1, 14, 114, 600, 1936, 3240, 1912, 128, 0, 0, 1, 16, 154, 1008, 4400, 11648, 15336, 6528, 256, 0
Offset: 0

Views

Author

Seiichi Manyama, Mar 11 2023

Keywords

Examples

			Square array begins:
  0,  0,   0,   0,    0,    0, ...
  1,  1,   1,   1,    1 ,   1, ...
  0,  2,   4,   6,    8,   10, ...
  0,  4,  14,  30,   52,   80, ...
  0,  8,  48, 144,  320,  600, ...
  0, 16, 164, 684, 1936, 4400, ...
		

Crossrefs

Column k=1..10 give A131577, A007070(n-1), A030192(n-1), A016129(n-1), A093145, A154237, A154248, A154348(n-1), A016175(n-1), A361293.
Main diagonal gives A360766.
Cf. A361432.

Programs

  • PARI
    T(n, k) = polcoef(lift(Mod('x, ('x-k)^2-k)^n), 1);

Formula

T(0,k) = 0, T(1,k) = 1; T(n,k) = 2 * k * T(n-1,k) - (k-1) * k * T(n-2,k).
T(n,k) = ((k + sqrt(k))^n - (k - sqrt(k))^n)/(2 * sqrt(k)) for k > 0.
G.f. of column k: x/(1 - 2 * k * x + (k-1) * k * x^2).
E.g.f. of column k: exp(k * x) * sinh(sqrt(k) * x) / sqrt(k) for k > 0.

A016282 Expansion of 1/((1-2*x)*(1-4*x)*(1-5*x)).

Original entry on oeis.org

1, 11, 83, 535, 3171, 17871, 97483, 520055, 2731091, 14179231, 72992283, 373347975, 1900290211, 9635660591, 48715157483, 245723238295, 1237206060531, 6220389909951, 31239388241083, 156746696495015, 785932504682051, 3938458614335311, 19727477439571083
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Mathematica
    CoefficientList[ Series[ 1/((1 - 2x)(1 - 4x)(1 - 5x)), {x, 0, 20} ], x ]
    LinearRecurrence[{11,-38,40},{1,11,83},30] (* Harvey P. Dale, Nov 29 2022 *)
  • PARI
    Vec(1/((1-2*x)*(1-4*x)*(1-5*x))+O(x^99)) \\ Charles R Greathouse IV, Sep 26 2012
  • Sage
    [(5^n - 2^n)/3-(4^n - 2^n)/2 for n in range(2,21)] # Zerinvary Lajos, Jun 05 2009
    

Formula

a(n) = (2/3)*2^n - 8*(4)^n + (25/3)*5^n. - Antonio Alberto Olivares, May 12 2012

A016295 Expansion of 1/((1-2x)(1-5x)(1-6x)).

Original entry on oeis.org

1, 13, 117, 905, 6461, 43953, 289717, 1868425, 11861421, 74423393, 462815717, 2858273145, 17556537181, 107373722833, 654414852117, 3977351721065, 24118423433741, 145982106270273, 882250466222917
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{13,-52,60},{1,13,117},20] (* Harvey P. Dale, Mar 26 2016 *)
  • Sage
    [(6^n - 2^n)/4-(5^n - 2^n)/3 for n in range(2,21)] # Zerinvary Lajos, Jun 05 2009

Formula

a(n) = A016129(n+1) - A016127(n+1). - Zerinvary Lajos, Jun 05 2009
a(n) = 13*a(n-1) - 52*a(n-2) + 60*a(n-3), n >= 3.
a(n) = 11*a(n-1) - 30*a(n-2) + 2^n, n >= 2. - Vincenzo Librandi, Mar 16 2011
a(n) = 7*a(n-1) - 10*a(n-2) + 6^n, n >= 2. - Vincenzo Librandi, Mar 16 2011
a(n) = 8*a(n-1) - 12*a(n-2) + 5^n, n >= 2. - Vincenzo Librandi, Mar 16 2011
a(n) = -5^(n+2)/3 + 9*6^n + 2^n/3. - R. J. Mathar, Mar 18 2011

A016633 Expansion of g.f. 1/((1-2*x)*(1-11*x)*(1-12*x)).

Original entry on oeis.org

1, 25, 447, 6989, 101759, 1417941, 19180519, 253983853, 3309800367, 42599540357, 542895780791, 6863463633117, 86197420501375, 1076563471968373, 13382900349107463, 165700329729679181, 2044564737700501583, 25152545442794015589, 308625999807796411735, 3778261997130507936445
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Magma
    [(648*12^n +2^(n+1)-5*11^(n+2))/45 : n in [0..20]]; // Vincenzo Librandi, Oct 09 2011
    
  • Mathematica
    CoefficientList[Series[1/((1 - 2 x) (1 - 11 x) (1 - 12 x)), {x, 0, 15}], x] (* Michael De Vlieger, Jan 31 2018 *)
  • PARI
    Vec(1/((1-2*x)*(1-11*x)*(1-12*x))+O(x^99)) \\ Charles R Greathouse IV, Sep 26 2012
  • Sage
    [(12^n - 2^n)/10-(11^n - 2^n)/9 for n in range(2,18)] # Zerinvary Lajos, Jun 05 2009
    

Formula

From Vincenzo Librandi, Oct 09 2011: (Start)
a(n) = (648*12^n + 2^(n+1) - 5*11^(n+2))/45.
a(n) = 23*a(n-1) - 132*a(n-2) + 2^n.
a(n) = 25*a(n-1) - 178*a(n-2) + 264*a(n-3), n >= 3. (End)
From Elmo R. Oliveira, Mar 26 2025: (Start)
E.g.f.: exp(2*x)*(648*exp(10*x) - 605*exp(9*x) + 2)/45.
a(n) = A016136(n+1) - A016135(n+1). (End)

A096039 Triangle read by rows: T(n,k) = (n+1,k)-th element of (M^5-M)/4, where M is the infinite lower Pascal's triangle matrix, 1<=k<=n.

Original entry on oeis.org

1, 6, 2, 31, 18, 3, 156, 124, 36, 4, 781, 780, 310, 60, 5, 3906, 4686, 2340, 620, 90, 6, 19531, 27342, 16401, 5460, 1085, 126, 7, 97656, 156248, 109368, 43736, 10920, 1736, 168, 8, 488281, 878904, 703116, 328104, 98406, 19656, 2604, 216, 9, 2441406
Offset: 1

Views

Author

Gary W. Adamson, Jun 17 2004

Keywords

Examples

			Triangle begins:
1;
6,       2;
31,     18,    3;
156,   124,   36,   4;
781,   780,  310,  60,  5;
3906, 4686, 2340, 620, 90, 6;
		

Crossrefs

Cf. A007318. First column gives A003463. Row sums give A016129.

Programs

  • Maple
    P:= proc(n) option remember; local M; M:= Matrix(n, (i, j)-> binomial(i-1, j-1)); (M^5-M)/4 end: T:= (n, k)-> P(n+1)[n+1, k]: seq(seq(T(n, k), k=1..n), n=1..11); # Alois P. Heinz, Oct 07 2009
  • Mathematica
    max = 11; M = Table[If[k > n, 0, Binomial[n, k]], {n, 0, max}, {k, 0, max} ];
    T = (MatrixPower[M, 5] - M)/4;
    Table[T[[n + 1]][[1 ;; n]] , {n, 1, max}] // Flatten (* Jean-François Alcover, May 24 2016 *)

Extensions

Edited with more terms by Alois P. Heinz, Oct 07 2009

A370762 Triangle read by rows: T(n,k) = 2 * (k mod 2 + 1) * T(n-1,floor(k/2)) + 1 with T(0,0) = 1 for 0 <= k <= 2^n-1.

Original entry on oeis.org

1, 3, 5, 7, 13, 11, 21, 15, 29, 27, 53, 23, 45, 43, 85, 31, 61, 59, 117, 55, 109, 107, 213, 47, 93, 91, 181, 87, 173, 171, 341, 63, 125, 123, 245, 119, 237, 235, 469, 111, 221, 219, 437, 215, 429, 427, 853, 95, 189, 187, 373, 183, 365, 363, 725, 175, 349, 347, 693, 343, 685, 683, 1365
Offset: 0

Views

Author

Seiichi Manyama, Mar 01 2024

Keywords

Examples

			First few rows are:
   1;
   3,  5;
   7, 13, 11,  21;
  15, 29, 27,  53, 23,  45,  43,  85;
  31, 61, 59, 117, 55, 109, 107, 213, 47, 93, 91, 181, 87, 173, 171, 341;
		

Crossrefs

Row sums give A016129.
Columns k=0 gives A000225(n+1).
Cf. A247648.

Programs

  • PARI
    T(n, k) = if(n==0, 1, 2*(k%2+1)*T(n-1, k\2)+1);
Previous Showing 21-30 of 30 results.