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.

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A126581 Freeman Dyson's list of values of k for which there is an identity of a certain type for the k-th power of the Dedekind eta function.

Original entry on oeis.org

3, 8, 10, 14, 15, 21, 24, 26, 28, 35, 36, 45, 48, 52, 55, 63, 66, 78, 80, 91, 99, 105, 120, 133, 136, 143, 153, 168, 171, 190, 195, 210, 224, 231, 248, 253, 255, 276, 288, 300, 323, 325, 351, 360, 378, 399, 406, 435, 440, 465, 483, 496, 528, 561, 575, 595, 624, 630
Offset: 1

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Author

N. J. A. Sloane, Mar 17 2007

Keywords

Comments

I. G. Macdonald showed that this list is the same as A003038 except for the presence of the number 26.

References

  • Freeman J. Dyson, Missed opportunities, Bull. Amer. Math. Soc. 78 (1972), 635-652.
  • N. Jacobson, Lie Algebras. Wiley, NY, 1962; pp. 141-146.
  • I. G. Macdonald, Some conjectures for root systems, SIAM J. Math. Anal., 13 (1982), 988-1007.

Crossrefs

Cf. A003038.

Extensions

Definition clarified by Jonathan Sondow, Mar 24 2013

A001066 Dimensions (sorted, with duplicates removed) of real simple Lie algebras.

Original entry on oeis.org

3, 6, 8, 10, 14, 15, 16, 20, 21, 24, 28, 30, 35, 36, 42, 45, 48, 52, 55, 56, 63, 66, 70, 72, 78, 80, 90, 91, 96, 99, 104, 105, 110, 120, 126, 132, 133, 136, 143, 153, 156, 160, 168, 171, 182, 190, 195, 198, 210, 224, 231, 240, 248, 253, 255, 266, 272, 276, 286, 288, 300, 306
Offset: 1

Views

Author

Richard E. Borcherds (reb(AT)math.berkeley.edu)

Keywords

Comments

The possible dimensions of real simple Lie algebras are the numbers n and 2n where n runs through the dimensions of the complex simple Lie algebras.

Examples

			6 is the dimension of the real simple Lie algebra SL_2(C).
		

References

  • Freeman J. Dyson, Missed opportunities, Bull. Amer. Math. Soc. 78 (1972), 635-652.
  • N. Jacobson, Lie Algebras. Wiley, NY, 1962; see pp. 141-146.

Crossrefs

Cf. A003038.
Subsequences, apart from some initial terms: A000217, A000384, A002378, A005563, A014105.

Programs

  • Haskell
    import Data.Set (deleteFindMin, fromList, insert)
    a001066 n = a001066_list !! (n-1)
    a001066_list = f (fromList [h, 2 * h]) $ tail a003038_list where
       h = head a003038_list
       f s (x:xs) = m : f (x `insert` (( 2 * x) `insert` s')) xs where
         (m, s') = deleteFindMin s
    -- Reinhard Zumkeller, Dec 16 2012
  • Mathematica
    max = 18; sa = Table[k*(k+2), {k, 1, max}]; sb = Table[k*(2k+1), {k, 2, max}]; sd := Table[k*(2k-1), {k, 4, max}]; se = {14, 52, 78, 133, 248}; Select[ Union[sa, 2*sa, sb, 2*sb, sd, 2*sd, se, 2*se], # <= max^2 &] (* Jean-François Alcover, Apr 02 2012, after A003038 *)

Formula

Numbers n and 2n as n runs through A003038.

Extensions

Entry revised by N. J. A. Sloane, Mar 16 2007
Showing 1-2 of 2 results.