The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A091823 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A091823

a(n) = 2*n^2 + 3*n - 1.
(history; published version)

#64 by N. J. A. Sloane at Mon Jun 17 15:49:47 EDT 2024

STATUS

proposed

approved

#63 by Stefano Spezia at Sun Jun 16 11:45:59 EDT 2024

STATUS

editing

proposed

#62 by Stefano Spezia at Sun Jun 16 11:43:36 EDT 2024

LINKS

Milan Janjic, <a href="http://www.pmfbl.org/janjic/">Two Enumerative Functions</a>. [Broken link]

#61 by Stefano Spezia at Sun Jun 16 11:41:39 EDT 2024

DATA

4, 13, 26, 43, 64, 89, 118, 151, 188, 229, 274, 323, 376, 433, 494, 559, 628, 701, 778, 859, 944, 1033, 1126, 1223, 1324, 1429, 1538, 1651, 1768, 1889, 2014, 2143, 2276, 2413, 2554, 2699, 2848, 3001, 3158, 3319, 3484, 3653, 3826, 4003, 4184, 4369, 4558, 4751

#60 by Stefano Spezia at Sun Jun 16 11:40:52 EDT 2024

FORMULA

E.g.f.: 1 + exp(x)*(2*x^2 + 5*x - 1). - Stefano Spezia, Jun 16 2024

STATUS

approved

editing

#59 by N. J. A. Sloane at Wed Sep 27 13:42:11 EDT 2023

STATUS

proposed

approved

#58 by Leo Tavares at Thu Aug 31 21:07:18 EDT 2023

STATUS

editing

proposed

Discussion

Fri Sep 01

01:38

Michel Marcus: I am not really convinced with the relevance of new formula

09:08

Leo Tavares: I think it shows a nice union between squares and triangles to form this series :)

#57 by Leo Tavares at Thu Aug 31 21:06:42 EDT 2023

LINKS

<a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).

#56 by Leo Tavares at Thu Aug 31 21:04:14 EDT 2023

LINKS

Leo Tavares, <a href="/A091823/a091823.jpg">Illustration: Square/Triangular Union</a>

FORMULA

a(n) = A000290(n+1) + 2*A000217(n) - 2. - Leo Tavares, Aug 31 2023

CROSSREFS

Cf. A000290, A000217.

STATUS

approved

editing

#55 by Charles R Greathouse IV at Thu Sep 08 08:45:13 EDT 2022

PROG

(MAGMAMagma) [2*n^2+3*n-1: n in [1..50]]; // Bruno Berselli, Mar 28 2014

Discussion

Thu Sep 08

08:45

OEIS Server: https://oeis.org/edit/global/2944