OFFSET
1,2
COMMENTS
(6k+1)*(12k+1)*(18k+1)*(36k+1) is a Carmichael number for all k in this sequence. - José María Grau Ribas, Feb 06 2012
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..5000 from Muniru A Asiru)
MAPLE
select(n->isprime(6*n+1) and isprime(12*n+1) and isprime(18*n+1) and isprime(36*n+1), [$1..12000]); # Muniru A Asiru, May 27 2018
MATHEMATICA
Select[Range[20000], PrimeQ[6 # + 1] && PrimeQ[12 # + 1] && PrimeQ[18 # + 1] && PrimeQ[36 # + 1] &]
Select[Range[12000], And@@PrimeQ[{6, 12, 18, 36}#+1]&] (* Harvey P. Dale, Mar 25 2013 *)
PROG
(PARI) forprime(p=2, 1e5, if(p%6!=1, next); if(isprime(2*p-1)&&isprime(3*p-2)&&isprime(6*p-5), print1(p\6", "))) \\ Charles R Greathouse IV, Feb 06 2012
(PARI) is(m, c=36)=!until(bittest(c\=2, 0)&&9>c+=3, isprime(m*c+1)||return) \\ M. F. Hasler, Apr 15 2015
(Magma) [n: n in [0..2*10^4] | IsPrime(6*n+1) and IsPrime(12*n+1) and IsPrime(18*n+1) and IsPrime(36*n+1)]; // Vincenzo Librandi, Apr 15 2015
(GAP) Filtered([1..12000], n->IsPrime(6*n+1) and IsPrime(12*n+1) and IsPrime(18*n+1) and IsPrime(36*n+1)); # Muniru A Asiru, May 27 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
José María Grau Ribas, Feb 03 2012
STATUS
approved