The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A133215

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A133215

Hexagonal numbers (A000384) which are sum of 2 other hexagonal numbers > 0.
(history; published version)

#14 by Joerg Arndt at Fri Sep 29 06:09:28 EDT 2017

STATUS

proposed

#13 by Michel Marcus at Fri Sep 29 06:05:36 EDT 2017

STATUS

editing

#12 by Michel Marcus at Fri Sep 29 06:05:32 EDT 2017

REFERENCES

Duke, W. and Schulze-Pillot, R. "Representations of Integers by Positive Ternary Quadratic Forms and Equidistribution of Lattice Points on Ellipsoids." Invent. Math. 99, 49-57, 1990.

LINKS

FORMULA

{x: x>0 and x in A000384 and x = A000384(i) + A000384(j) for i>0 and j>0}, where = A000384 = {n*(2*n-1) for n > 0}.

STATUS

approved

#11 by Charles R Greathouse IV at Thu Nov 21 12:49:06 EST 2013

MATHEMATICA

With[{upto=60000}, Select[Union[Total/@Subsets[Table[n(2n-1), {n, Ceiling[ (1+Sqrt[1+8upto])/4]}], {2}]], IntegerQ[(1+Sqrt[1+8#])/4]&&#<=upto&]] (* From Harvey P. Dale, Jul 24 2011 *)

Discussion

Thu Nov 21

12:49

OEIS Server: https://oeis.org/edit/global/2062

#10 by Joerg Arndt at Tue Aug 28 03:13:56 EDT 2012

STATUS

proposed

#9 by Donovan Johnson at Tue Aug 28 03:09:07 EDT 2012

STATUS

editing

#8 by Donovan Johnson at Tue Aug 28 03:08:14 EDT 2012

LINKS

Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/HexagonalNumber.html">Hexagonal Number</a>.

#7 by Donovan Johnson at Tue Aug 28 03:07:31 EDT 2012

LINKS

STATUS

approved

#6 by Russ Cox at Fri Mar 30 18:40:43 EDT 2012

AUTHOR

Jonathan Vos Post (jvospost3(AT)gmail.com), Dec 18 2007

Discussion

Fri Mar 30

18:40

OEIS Server: https://oeis.org/edit/global/228

#5 by Russ Cox at Fri Mar 30 17:34:57 EDT 2012

EXTENSIONS

Added missing term 276 and a(8)-a(35) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Sep 27 2008

Discussion

Fri Mar 30

17:34

OEIS Server: https://oeis.org/edit/global/163