OFFSET
1,1
COMMENTS
Number of terms less than 10^k, k=1,2,3,...: 2, 5, 10, 21, 39, 66, 118, 213, 419, 770, 1486, 2886, 5575, 11096, 22338, 44710, 89992, 182554, 370614, 754201, 1541613, 3159885, ... - Muniru A Asiru, Jan 29 2018
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
1*2*3 = 6; 6-1 = 5, a prime, so it is a term; 6+1 = 7, a prime, so it is a term;
2*3*4 = 24; 24-1 = 23, a prime so is a term, 24+1 = 25, not a prime and so not a term;
100*101*102 = 1030200; 1030200+1 = 1030201 is a term.
MAPLE
select(isprime, [seq(seq((k-1)*k*(k+1)+q, q=[-1, 1]), k=1..100)]); # Robert Israel, Jan 04 2018
MATHEMATICA
lst = {}; k = 1; While[k < 61, p = k^3 - k; If[ PrimeQ[p -1], AppendTo[lst, p -1]]; If[PrimeQ[p +1], AppendTo[lst, p +1]]; k++]; lst (* Robert G. Wilson v, Oct 18 2017 *)
PROG
(PARI) lista(nn) = {for (n=1, nn, if (isprime(p=n*(n+1)*(n+2)-1), print1(p, ", ")); if (isprime(p=n*(n+1)*(n+2)+1), print1(p, ", ")); ); } \\ Michel Marcus, Oct 19 2017
(GAP) Filtered(Set(Flat(List([1..60], k -> List([1, -1], q -> (k-1)*k*(k+1)+q)))), IsPrime); # Muniru A Asiru, Jan 29 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Rajarshi Maiti, Oct 18 2017
EXTENSIONS
Corrected and extended by Robert G. Wilson v, Oct 18 2017
STATUS
approved