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 1-4 of 4 results.

A017137 a(n) = 8*n + 6.

Original entry on oeis.org

6, 14, 22, 30, 38, 46, 54, 62, 70, 78, 86, 94, 102, 110, 118, 126, 134, 142, 150, 158, 166, 174, 182, 190, 198, 206, 214, 222, 230, 238, 246, 254, 262, 270, 278, 286, 294, 302, 310, 318, 326, 334, 342, 350, 358, 366, 374, 382, 390, 398, 406, 414, 422, 430
Offset: 0

Views

Author

N. J. A. Sloane, Dec 11 1996

Keywords

Comments

First differences of A002943. - Aaron David Fairbanks, May 13 2014

Examples

			G.f. = 6 + 14*x + 22*x^2 + 30*x^3 + 38*x^4 + 46*x^5 + 54*x^6 + 62*x^7 + ...
		

Crossrefs

Programs

Formula

a(n) = 2*A004767(n) = A000290(A017245(n)) - A156676(n+1). - Reinhard Zumkeller, Jul 13 2010
a(n) = 2*a(n-1) - a(n-2). - Vincenzo Librandi, Jun 07 2011
A089911(3*a(n)) = 4. - Reinhard Zumkeller, Jul 05 2013
From Michael Somos, May 15 2014: (Start)
G.f.: (6 + 2*x)/(1 - x)^2.
E.g.f.: (6 + 8*x)*exp(x). (End)
Sum_{n>=0} (-1)^n/a(n) = (Pi + log(3-2*sqrt(2)))/(8*sqrt(2)). - Amiram Eldar, Dec 11 2021
a(n) = A016825(2*n+1). - Elmo R. Oliveira, Apr 12 2025

A017245 a(n) = 9*n + 7.

Original entry on oeis.org

7, 16, 25, 34, 43, 52, 61, 70, 79, 88, 97, 106, 115, 124, 133, 142, 151, 160, 169, 178, 187, 196, 205, 214, 223, 232, 241, 250, 259, 268, 277, 286, 295, 304, 313, 322, 331, 340, 349, 358, 367, 376, 385, 394, 403, 412, 421, 430, 439, 448, 457, 466, 475, 484
Offset: 0

Views

Author

Keywords

Comments

Numbers whose digital root is 7. - Halfdan Skjerning, Mar 15 2018

Crossrefs

Programs

Formula

a(n)^2 = A156676(n+1) + A017137(n). - Reinhard Zumkeller, Jul 13 2010
From Vincenzo Librandi, Apr 30 2015: (Start)
G.f.: (7+2*x)/(1-x)^2.
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>2. (End)
E.g.f.: exp(x)*(7 + 9*x). - Stefano Spezia, Dec 08 2024

A156772 a(n) = 729*n - 198.

Original entry on oeis.org

531, 1260, 1989, 2718, 3447, 4176, 4905, 5634, 6363, 7092, 7821, 8550, 9279, 10008, 10737, 11466, 12195, 12924, 13653, 14382, 15111, 15840, 16569, 17298, 18027, 18756, 19485, 20214, 20943, 21672, 22401, 23130, 23859, 24588, 25317, 26046
Offset: 1

Views

Author

Vincenzo Librandi, Feb 15 2009

Keywords

Comments

The identity (6561*n^2 - 3564*n + 485)^2 - (81*n^2 - 44*n + 6)*(729*n - 198)^2 = 1 can be written as A156774(n)^2 - A156676(n)*a(n)^2 = 1.

Crossrefs

Programs

  • Magma
    I:=[531, 1260]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..50]];
    
  • Mathematica
    LinearRecurrence[{2,-1}, {531,1260}, 40]
  • PARI
    a(n)=729*n-198 \\ Charles R Greathouse IV, Dec 23 2011
    
  • Sage
    [9*(81*n -22) for n in [1..50]] # G. C. Greubel, Jun 19 2021

Formula

a(n) = 2*a(n-1) - a(n-2).
G.f.: x*(531 + 198*x)/(1-x)^2.
E.g.f.: 9*(22 - (22 - 81*x)*exp(x)). - G. C. Greubel, Jun 19 2021

A156774 a(n) = 6561*n^2 - 3564*n + 485.

Original entry on oeis.org

485, 3482, 19601, 48842, 91205, 146690, 215297, 297026, 391877, 499850, 620945, 755162, 902501, 1062962, 1236545, 1423250, 1623077, 1836026, 2062097, 2301290, 2553605, 2819042, 3097601, 3389282, 3694085, 4012010, 4343057, 4687226
Offset: 0

Views

Author

Vincenzo Librandi, Feb 15 2009

Keywords

Comments

The identity (6561*n^2 - 3564*n + 485)^2 - (81*n^2 - 44*n + 6)*(729*n - 198)^2 = 1 can be written as a(n)^2 - A156676(n)*A156772(n)^2 = 1 for n>0.

Crossrefs

Programs

  • Magma
    I:=[485, 3482, 19601]; [n le 3 select I[n] else 3*Self(n-1)-3*Self(n-2)+1*Self(n-3): n in [1..40]];
    
  • Mathematica
    LinearRecurrence[{3,-3,1},{485,3482,19601},40]
    Table[6561n^2-3564n+485,{n,0,30}] (* Harvey P. Dale, Dec 09 2020 *)
  • PARI
    a(n)= 6561*n^2-3564*n+485 \\ Charles R Greathouse IV, Dec 23 2011
    
  • Sage
    [485 -3564*n +6561*n^2 for n in (0..40)] # G. C. Greubel, Jun 21 2021

Formula

a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3).
G.f.: (485 + 2027*x + 10610*x^2)/(1-x)^3.
E.g.f.: (485 + 2997*x + 6561*x^2)*exp(x). - G. C. Greubel, Jun 21 2021

Extensions

Edited by Charles R Greathouse IV, Jul 25 2010
Showing 1-4 of 4 results.