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 1-2 of 2 results.

A051871 19-gonal (or enneadecagonal) numbers: n(17n-15)/2.

Original entry on oeis.org

0, 1, 19, 54, 106, 175, 261, 364, 484, 621, 775, 946, 1134, 1339, 1561, 1800, 2056, 2329, 2619, 2926, 3250, 3591, 3949, 4324, 4716, 5125, 5551, 5994, 6454, 6931, 7425, 7936, 8464, 9009, 9571, 10150, 10746, 11359, 11989, 12636, 13300
Offset: 0

Views

Author

N. J. A. Sloane, Dec 15 1999

Keywords

Comments

Sequence found by reading the line from 0, in the direction 0, 19, ... and the parallel line from 1, in the direction 1, 54, ..., in the square spiral whose vertices are the generalized 19-gonal numbers. - Omar E. Pol, Jul 18 2012
Partial sums of A215137 (17n + 1). - Jeremy Gardiner, Aug 04 2012

Examples

			a(1) = 17 * 1 + 0 - 16 = 1.
a(2) = 17 * 2 + 1 - 16 = 19.
a(3) = 17 * 3 + 19 - 16 = 54. - _Vincenzo Librandi_, Aug 06 2010
		

References

  • Albert H. Beiler, Recreations in the Theory of Numbers, Dover, N.Y., 1964, p. 189.
  • Elena Deza and Michel M. Deza, Figurate numbers, World Scientific Publishing (2012), page 6.

Programs

Formula

a(n) = n(17n-15)/2.
G.f.: x*(1+16*x)/(1-x)^3. - Bruno Berselli, Feb 04 2011
a(n) = 17*n + a(n-1) - 16 (with a(0) = 0). - Vincenzo Librandi, Aug 06 2010
a(17*a(n) + 137*n + 1) = a(17*a(n) + 137*n) + a(17*n+1). - Vladimir Shevelev, Jan 24 2014
Product_{n>=2} (1 - 1/a(n)) = 17/19. - Amiram Eldar, Jan 22 2021
E.g.f.: exp(x)*(x + 17*x^2/2). - Nikolaos Pantelidis, Feb 06 2023

A154612 a(n) = 17*n + 7.

Original entry on oeis.org

7, 24, 41, 58, 75, 92, 109, 126, 143, 160, 177, 194, 211, 228, 245, 262, 279, 296, 313, 330, 347, 364, 381, 398, 415, 432, 449, 466, 483, 500, 517, 534, 551, 568, 585, 602, 619, 636, 653, 670, 687, 704, 721, 738, 755, 772, 789, 806, 823, 840, 857, 874, 891
Offset: 0

Views

Author

Vincenzo Librandi, Jan 15 2009

Keywords

Comments

a(n)^4 = Sum_{j=0..(16*n*(17*n+14)+46)} (-1)^j*(119*n^2 + 98*n + 20 + j)^2. - Bruno Berselli, Apr 30 2010

Examples

			For n=5, a(5)^4 = 92^4 = 71639296 = 3485^2-3486^2+3487^2-..+11449^2-11450^2+11451^2. - _Bruno Berselli_, Apr 30 2010
		

Crossrefs

Sequences of the form 17*n+q: A361692 (q=-1), A008599 (q=0), A215137 (q=1), this sequence (q=7).

Programs

Formula

G.f.: (7+10*x)/(1-x)^2. - Colin Barker, Jan 09 2012
a(n) = 2*a(n-1) - a(n-2). - Vincenzo Librandi, Feb 26 2012
E.g.f.: (7 + 17*x)*exp(x). - G. C. Greubel, May 31 2024

Extensions

Offset corrected by Bruno Berselli, Aug 16 2010
Showing 1-2 of 2 results.