|
|
A249798
|
|
Numbers k such that the product of the first k primes minus the (k+1)-th prime is prime.
|
|
1
|
|
|
3, 4, 5, 6, 8, 22, 23, 24, 35, 73, 83, 147, 553, 1098, 1115, 1542, 2097, 2149
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
FORMULA
|
|
|
EXAMPLE
|
p(1)*p(2)*p(3)*p(4) - p(5) = 2*3*5*7 - 11 = 199. 199 is prime, therefore 4 is in the sequence.
|
|
MATHEMATICA
|
Select[Range[1000], PrimeQ[Times@@(Prime[Range[#]])-Prime[#+1]]&]
|
|
PROG
|
(PARI) lista(nn) = {prp = 1; for(n=1, nn, prp *= prime(n); if (isprime(prp-prime(n+1)), print1(n, ", ")); ); } \\ Michel Marcus, Nov 06 2014
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,more
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|