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A118333
Largest prime factor of n!! + (n+1)!!.
2
2, 3, 5, 11, 23, 7, 17, 163, 443, 29, 73, 251, 4027, 2477, 499, 199, 883, 47, 2671, 308333, 2099, 859, 510481, 10429, 514519, 29629, 51713, 42337, 5407, 13841, 151733, 2448023843, 3133033, 89101, 61613, 19448653009, 50136277, 63259211
OFFSET
0,1
COMMENTS
First five terms coincide with A118332 because n!! + (n+1)!! is prime for n = 0, 1, 2, 3, 4. At n>4, n!! + (n+1)!! is always composite.
LINKS
MATHEMATICA
Table[FactorInteger[n!!+(n+1)!! ][[ -1, 1]], {n, 0, 40}]
FactorInteger[#][[-1, 1]]&/@(Total/@Partition[Range[0, 40]!!, 2, 1]) (* Harvey P. Dale, Mar 22 2019 *)
CROSSREFS
Cf. A118332.
Sequence in context: A073880 A376856 A118332 * A131101 A188534 A214196
KEYWORD
nonn
AUTHOR
Zak Seidov, Apr 23 2006
STATUS
approved