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A184775
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Numbers k such that floor(k*sqrt(2)) is prime.
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6
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2, 4, 5, 8, 14, 21, 22, 29, 31, 38, 42, 48, 52, 56, 59, 63, 69, 72, 73, 76, 80, 90, 93, 97, 106, 107, 123, 127, 128, 137, 140, 141, 158, 161, 162, 165, 169, 171, 178, 182, 186, 192, 196, 199, 220, 222, 239, 246, 247, 250, 254, 260, 264, 268, 271, 281, 284, 298, 305, 311, 318
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OFFSET
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1,1
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COMMENTS
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Chua, Park, & Smith prove a general result that implies that, for any m, there is a constant C(m) such that a(n+m) - a(n) < C(m) infinitely often. - Charles R Greathouse IV, Jul 01 2022
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LINKS
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EXAMPLE
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MATHEMATICA
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r=2^(1/2); s=r/(r-1);
Table[a[n], {n, 1, 120}]
t1={}; Do[If[PrimeQ[a[n]], AppendTo[t1, a[n]]], {n, 1, 600}]; t1
t2={}; Do[If[PrimeQ[a[n]], AppendTo[t2, n]], {n, 1, 600}]; t2
t3={}; Do[If[MemberQ[t1, Prime[n]], AppendTo[t3, n]], {n, 1, 300}]; t3
t4={}; Do[If[PrimeQ[b[n]], AppendTo[t4, b[n]]], {n, 1, 600}]; t4
t5={}; Do[If[PrimeQ[b[n]], AppendTo[t5, n]], {n, 1, 600}]; t5
t6={}; Do[If[MemberQ[t4, Prime[n]], AppendTo[t6, n]], {n, 1, 300}]; t6
(* the lists t1, t2, t3, t4, t5, t6 match the sequences
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PROG
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(PARI) isok(n) = isprime(floor(n*sqrt(2))); \\ Michel Marcus, Apr 10 2018
(Python)
from itertools import count, islice
from math import isqrt
from sympy import isprime
def A184775_gen(): # generator of terms
return filter(lambda k:isprime(isqrt(k**2<<1)), count(1))
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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