A171643 Primes p such that the nearest integer to p*LN2 is prime, LN2=natural logarithm of 2, LN2~0.693147180..

3, 5, 7, 19, 53, 59, 97, 103, 149, 157, 163, 197, 227, 241, 331, 347, 379, 409, 443, 449, 457, 503, 509, 547, 607, 659, 691, 709, 751, 821, 911, 953, 971, 977, 997, 1049, 1109, 1187, 1193, 1231, 1237, 1279, 1409, 1429, 1439, 1487, 1499, 1531, 1583, 1663, 1721

Offset

1,1

Links

Table of n, a(n) for n=1..51.

Mathematica

lst={}; Do[p=Prime[n]; If[PrimeQ[Round[p*Log[2]]], AppendTo[lst, p]], {n, 6!}]; lst
nil2[n_]:=Module[{c=n Log[2], ce, fl}, ce=Ceiling[c]; fl=Floor[c]; If[ c-fl < ce- c, PrimeQ[fl], PrimeQ[ce]]]; Select[Prime[Range[300]], nil2] (* Harvey P. Dale, May 05 2019 *)

Crossrefs

Cf. A116671, A116968, A117763, A118484, A118625, A118786, A118796

Sequence in context: A322302 A154526 A126144 * A072002 A217651 A362417

Adjacent sequences: A171640 A171641 A171642 * A171644 A171645 A171646

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Dec 13 2009

Status

approved