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A173830 Primes of the form p - floor(sqrt(p)), p prime. 1
2, 3, 5, 13, 19, 31, 37, 41, 59, 71, 97, 103, 137, 139, 151, 197, 241, 313, 331, 389, 401, 419, 487, 499, 563, 569, 577, 593, 683, 701, 769, 811, 877, 881, 907, 911, 1019, 1031, 1129, 1153, 1283, 1291, 1409, 1433, 1451, 1567, 1579, 1597, 1627, 1741, 1747, 1759 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Primes k such that k + floor(sqrt(k + floor(sqrt(k)))) is prime (see A000037). - Ivan N. Ianakiev, Jun 23 2022

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

MATHEMATICA

f[n_]:=n-Floor[Sqrt[n]]; lst={}; Do[p=Prime[n]; If[PrimeQ[f[p]], AppendTo[lst, f[p]]], {n, 7!}]; lst

PROG

(PARI) forprime(p=2, 1e4, if(isprime(t=p-sqrtint(p)), print1(t", "))) \\ Charles R Greathouse IV, Apr 15 2012

CROSSREFS

Cf. A086086, A000037.

Sequence in context: A215371 A164958 A145908 * A224223 A238497 A061305

Adjacent sequences: A173827 A173828 A173829 * A173831 A173832 A173833

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, Feb 25 2010

STATUS

approved

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Last modified December 6 10:38 EST 2022. Contains 358630 sequences. (Running on oeis4.)