A139059
Primes of the form (5+k!)/5.
Original entry on oeis.org
1009, 72577, 7983361, 17435658241, 24329020081766401, 5170403347776995328001, 23924444173096038912392632299131543012876746752000000001
Offset: 1
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[ a: n in [1..50] | IsPrime(a) and b mod 5 eq 0 where a is b div 5 where b is Factorial(n)+5 ];
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a = {}; Do[If[PrimeQ[(n! + 5)/5], AppendTo[a, (n! + 5)/5]], {n, 1, 50}]; a
Select[(5+Range[50]!)/5,PrimeQ] (* Harvey P. Dale, Dec 04 2020 *)
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for(k=5,1e3,if(ispseudoprime(t=(5+k!)/5),print1(t", "))) \\ Charles R Greathouse IV, Jul 15 2011
A139151
a(n) = (n!+4)/4.
Original entry on oeis.org
7, 31, 181, 1261, 10081, 90721, 907201, 9979201, 119750401, 1556755201, 21794572801, 326918592001, 5230697472001, 88921857024001, 1600593426432001, 30411275102208001, 608225502044160001, 12772735542927360001
Offset: 4
A139149
a(n) = (n!+2)/2.
Original entry on oeis.org
2, 4, 13, 61, 361, 2521, 20161, 181441, 1814401, 19958401, 239500801, 3113510401, 43589145601, 653837184001, 10461394944001, 177843714048001, 3201186852864001, 60822550204416001, 1216451004088320001, 25545471085854720001, 562000363888803840001
Offset: 2
(1!+2)/2 = 3/2 is not an integer.
a(2) = (2!+2)/2 = 2.
Offsets for above sequences are Kempner numbers
A002034.
For smallest number of the form (m!+n)/n see
A139148.
Cf.
A007749,
A020458,
A082672,
A089085,
A089130,
A117141,
A137390,
A139056-
A139066,
A139068,
A139070-
A139075,
A139157,
A139159-
A139162.
Showing 1-3 of 3 results.
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