

A279098


Numbers k such that prime(k) divides primorial(j) + 1 for exactly one integer j.


5



1, 2, 4, 8, 11, 17, 18, 21, 25, 32, 34, 35, 39, 40, 42, 47, 48, 58, 63, 65, 66, 67, 69, 90, 91, 97, 105, 110, 122, 140, 144, 151, 152, 162, 166, 168, 173, 174, 175, 179, 180, 186, 205, 207, 208, 210, 211, 218, 233, 243, 249, 256, 261, 262, 297, 308, 316, 318
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,2


COMMENTS

As used here, "primorial(j)" refers to the product of the first j primes, i.e., A002110(j).
Primorial(j) + 1 is the jth Euclid number, A006862(j).


LINKS

Giovanni Resta, Table of n, a(n) for n = 1..10000


EXAMPLE

59 is not in this sequence because both primorial(7) + 1 = 510511 and primorial(17) + 1 = 1922760350154212639071 are divisible by prime(59) = 277.


MATHEMATICA

np[1]=1; np[n_] := Block[{c=0, p=Prime[n], trg, x=1}, trg = p1; Do[x = Mod[x Prime[k], p]; If[trg == x, c++], {k, n1}]; c]; Select[Range[262], np[#] == 1 &] (* Giovanni Resta, Mar 29 2017 *)


CROSSREFS

Subsequence of A279097 (which also includes numbers k such that prime(k) divides primorial(j) + 1 for more than one integer j).
Cf. A000040, A002110, A006862, A113165, A279099, A283928.
Sequence in context: A018320 A153195 A279097 * A010068 A295674 A120632
Adjacent sequences: A279095 A279096 A279097 * A279099 A279100 A279101


KEYWORD

nonn


AUTHOR

Jon E. Schoenfield, Mar 24 2017


STATUS

approved



