OFFSET
1,1
COMMENTS
The next term a(10) has 95 digits which is too large to show in data section.
a(16) has 1181 digits, hence not included in b-file.
Primes for indices 3, 5, 9, 11, 14, 20, 27, 41, 54, 65, 81, 83, 105, 315, 323, 515, ... - Robert G. Wilson v, Aug 07 2014
LINKS
K. D. Bajpai, Table of n, a(n) for n = 1..15
EXAMPLE
m = 3: m! - (m+1)! + (m+2)! + 1 = 103, which is prime, hence appears in the sequence.
m = 5: m! - (m+1)! + (m+2)! + 1 = 4441, which is prime, hence appears in the sequence.
MATHEMATICA
Select[Table[n! - (n + 1)! + (n + 2)! + 1, {n, 200}], PrimeQ[#] &]
Select[#[[1]]-#[[2]]+#[[3]]+1&/@Partition[Range[70]!, 3, 1], PrimeQ] (* Harvey P. Dale, Aug 20 2021 *)
PROG
(PARI)
a(n) = p=n!-(n+1)!+(n+2)!+1; if(ispseudoprime(p), return(p))
n=1; while(n<100, if(a(n), print1(a(n), ", ")); n++) \\ Derek Orr, Jul 27 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
K. D. Bajpai, Jul 24 2014
STATUS
approved