OFFSET
1,1
COMMENTS
Primes p such that p + 3*A053644(p) is also prime. - Robert Israel, Jan 13 2016
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
p = 5: 4 + 5 + 8 = 17 (is prime).
p = 7: 4 + 7 + 8 = 19 (is prime).
p = 31: 16 + 31 + 32 = 79 (is prime).
p = 43: 32 + 43 + 64 = 139 (is prime).
p = 71: 64 + 71 + 128 = 263 (is prime).
p = 89: 64 + 89 + 128 = 281 (is prime).
MAPLE
select(t -> isprime(t) and isprime(t + 3*2^ilog2(t)), [seq(i, i=3..10^4, 2)]); # Robert Israel, Jan 13 2016
MATHEMATICA
Select[Prime@ Range@ 165, Function[k, PrimeQ[(2^k) + # + (2^(k + 1))]]@ Floor@ Log2@ # &] (* Michael De Vlieger, Jan 12 2016 *)
lp2Q[p_]:=Module[{k=Floor[Log[2, p]]}, PrimeQ[2^k+p+2^(k+1)]]; Select[ Prime[ Range[200]], lp2Q] (* Harvey P. Dale, Nov 02 2021 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Emre APARI, Jan 12 2016
STATUS
approved