The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A138805 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A138805

Theta series of quadratic form x^2 + x*y + 7*y^2.
(history; published version)

#18 by Vaclav Kotesovec at Fri Dec 29 03:49:21 EST 2023

STATUS

reviewed

approved

#17 by Michel Marcus at Fri Dec 29 02:12:48 EST 2023

STATUS

proposed

reviewed

#16 by Amiram Eldar at Fri Dec 29 00:48:20 EST 2023

STATUS

editing

proposed

#15 by Amiram Eldar at Fri Dec 29 00:20:00 EST 2023

LINKS

Michael Somos, <a href="/A010815/a010815.txt">Introduction to Ramanujan theta functions</a>, 2019.

Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/RamanujanThetaFunctions.html">Ramanujan Theta Functions</a>.

FORMULA

Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = 2*Pi/(3*sqrt(3)) = 1.209199... (A248897). - Amiram Eldar, Dec 29 2023

CROSSREFS

Cf. A004016, A138806, A248897.

Cf. A000122, A000700, A010054, A121373.

KEYWORD

nonn,easy

STATUS

approved

editing

#14 by Charles R Greathouse IV at Thu Sep 08 08:45:33 EDT 2022

PROG

(MAGMAMagma) A := Basis( ModularForms( Gamma1(27), 1), 87); A[1] + 2*A[2] + 2*A[5] + 4*A[8] + 6*A[10] + 4*A[14] + 2*A[15]; /* Michael Somos, Sep 08 2015 */

Discussion

Thu Sep 08

08:45

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

#13 by Charles R Greathouse IV at Fri Mar 12 22:24:45 EST 2021

LINKS

M. Michael Somos, <a href="/A010815/a010815.txt">Introduction to Ramanujan theta functions</a>

Discussion

Fri Mar 12

22:24

OEIS Server: https://oeis.org/edit/global/2897

#12 by N. J. A. Sloane at Wed Nov 13 21:58:48 EST 2019

LINKS

M. Somos, <a href="http://somos.crg4.comA010815/multiqa010815.htmltxt">Introduction to Ramanujan theta functions</a>

Discussion

Wed Nov 13

21:58

OEIS Server: https://oeis.org/edit/global/2832

#11 by Susanna Cuyler at Thu Dec 14 21:17:19 EST 2017

STATUS

proposed

approved

#10 by G. C. Greubel at Thu Dec 14 19:29:22 EST 2017

STATUS

editing

proposed

#9 by G. C. Greubel at Thu Dec 14 19:29:14 EST 2017

LINKS

G. C. Greubel, <a href="/A138805/b138805.txt">Table of n, a(n) for n = 0..10000</a>

STATUS

approved

editing