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A171643
Primes p such that the nearest integer to p*LN2 is prime, LN2=natural logarithm of 2, LN2~0.693147180..
0
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
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 *)
KEYWORD
nonn
AUTHOR
STATUS
approved