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Revision History for A284826

(Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A284826

Irregular triangle T(n,k) for 1 <= k <= (n+1)/2: T(n,k) = number of primitive (aperiodic) palindromic structures of length n using exactly k different symbols.
(history; published version)

#28 by Bruno Berselli at Mon Jun 12 08:08:48 EDT 2017

STATUS

reviewed

approved

#27 by Joerg Arndt at Mon Jun 12 07:46:40 EDT 2017

STATUS

proposed

reviewed

#26 by Jean-François Alcover at Mon Jun 12 07:45:17 EDT 2017

STATUS

editing

proposed

#25 by Jean-François Alcover at Mon Jun 12 07:45:12 EDT 2017

MATHEMATICA

T[n_, k_] := DivisorSum[n, MoebiusMu[n/#]*StirlingS2[Ceiling[#/2], k]&];

Table[T[n, k], {n, 1, 15}, {k, 1, Floor[(n+1)/2]}] // Flatten (* Jean-François Alcover, Jun 12 2017, from 2nd formula *)

STATUS

approved

editing

#24 by N. J. A. Sloane at Fri May 19 10:39:40 EDT 2017

REFERENCES

M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia. [See A056391 for pdf file of Chap. 2]

Discussion

Fri May 19

10:39

OEIS Server: https://oeis.org/edit/global/2652

#23 by N. J. A. Sloane at Sun Apr 09 10:39:46 EDT 2017

STATUS

reviewed

approved

#22 by Joerg Arndt at Sun Apr 09 03:04:54 EDT 2017

STATUS

proposed

reviewed

#21 by Andrew Howroyd at Sat Apr 08 22:22:32 EDT 2017

STATUS

editing

proposed

#20 by Andrew Howroyd at Sat Apr 08 22:18:54 EDT 2017

CROSSREFS

Partial row sums include A056476, A056477, A056478, A056479, A056480.

Discussion

Sat Apr 08

22:22

Andrew Howroyd: Tweaking PARI to use ! instead of factorial (which seems to be gamma fun) - probably doesn't make much difference but this is safer+better.

#19 by Andrew Howroyd at Sat Apr 08 22:14:40 EDT 2017

PROG

a(n, k) = sum(j=0, k, b(n, k-j)*binomial(k, j)*(-1)^j)\factorial(/k)!;

STATUS

approved

editing