A073105 Least k such that there are n primes among the numbers x*2^n + 1 for 1 <= x <= k.

1, 3, 9, 12, 14, 12, 26, 46, 38, 49, 59, 46, 90, 73, 141, 117, 114, 127, 179, 151, 131, 238, 305, 250, 245, 258, 290, 468, 384, 345, 497, 403, 495, 502, 564, 543, 576, 624, 575, 561

Offset

1,2

Links

Table of n, a(n) for n=1..40.

Prog

(PARI) a(n)=if(n<0, 0, s=1; while(sum(k=1, s, isprime(k*2^n+1))<n, s++); s)

Crossrefs

Sequence in context: A168400 A310318 A310319 * A356101 A073536 A077468

Adjacent sequences: A073102 A073103 A073104 * A073106 A073107 A073108

Keyword

easy,nonn

Author

Benoit Cloitre, Aug 19 2002

Status

approved