The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A129741 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A129741

List of primitive prime divisors of the Somos-4 sequence (A006720) in their order of occurrence.
(history; published version)

#14 by Harvey P. Dale at Sat May 25 14:05:32 EDT 2024

STATUS

editing

approved

#13 by Harvey P. Dale at Sat May 25 14:05:29 EDT 2024

MATHEMATICA

DeleteDuplicates[DeleteCases[Flatten[FactorInteger[#][[;; , 1]]&/@RecurrenceTable[{a[0]==a[1]== a[2]==a[3]==1, a[n]==(a[n-1]a[n-3]+a[n-2]^2)/a[n-4]}, a, {n, 30}]], 1]] (* Harvey P. Dale, May 25 2024 *)

STATUS

approved

editing

#12 by Joerg Arndt at Thu Sep 14 03:56:28 EDT 2017

STATUS

proposed

approved

#11 by Michel Marcus at Thu Sep 14 02:22:40 EDT 2017

STATUS

editing

proposed

#10 by Michel Marcus at Thu Sep 14 02:22:35 EDT 2017

REFERENCES

G. Everest et al., Primes generated by recurrence sequences, Amer. Math. Monthly, 114 (No. 5, 2007), 417-431.

LINKS

G. Everest et al., <a href="http://www.jstor.org/stable/27642221">Primes generated by recurrence sequences</a>, Amer. Math. Monthly, 114 (No. 5, 2007), 417-431.

EXTENSIONS

Corrected the order Order of some of the terms - _corrected by _T. D. Noe_, Nov 19 2013

STATUS

approved

editing

#9 by T. D. Noe at Tue Nov 19 19:59:17 EST 2013

STATUS

editing

approved

#8 by T. D. Noe at Tue Nov 19 19:59:14 EST 2013

CROSSREFS

Cf. A227199 (primes in this sequence).

STATUS

approved

editing

#7 by T. D. Noe at Tue Nov 19 18:41:29 EST 2013

STATUS

editing

approved

#6 by T. D. Noe at Tue Nov 19 18:41:25 EST 2013

MATHEMATICA

a[0] = a[1] = a[2] = a[3] = 1; a[n_] := a[n] = (a[n - 1] a[n - 3] + a[n - 2]^2)/a[n - 4]; t = Array[a, 30]; t2 = {}; ps = {}; Do[f = Transpose[FactorInteger[t[[n]]]][[1]]; c = Complement[f, ps]; t2 = Join[t2, c]; ps = Union[ps, c], {n, 4, 30}]; t2 (* T. D. Noe, Nov 19 2013 *)

#5 by T. D. Noe at Tue Nov 19 18:39:56 EST 2013

MATHEMATICA

a[0] = a[1] = a[2] = a[3] = 1; a[n_] := a[n] = (a[n - 1] a[n - 3] + a[n - 2]^2)/a[n - 4]; t = Array[a, 30]; t2 = {}; ps = {}; Do[f =Transpose[FactorInteger[t[[n]]]][[1]]; c = Complement[f, ps]; t2 = Join[t2, c]; ps = Union[ps, c], {n, 4, 30}]; t2 (* T. D. Noe, Nov 19 2013 *)

EXTENSIONS

Corrected the order of some of the terms - T. D. Noe, Nov 19 2013