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A065377
Primes not of the form p + k^2, with p prime and k > 0.
7
2, 5, 13, 31, 37, 61, 127, 379, 439, 571, 829, 991, 1549, 3319, 7549
OFFSET
1,1
COMMENTS
Probably finite and 7549 is the last entry. - Robert G. Wilson v, Nov 05 2001
No more terms below 10^9. - Mauro Fiorentini, Mar 02 2020
MAPLE
N:= 10^6: # to get all entries <= N
Primes:= select(isprime, {2, seq(2*i+1, i=1..floor((N-1)/2))}):
A:= NULL:
for i from 1 to nops(Primes) do
for k from floor(sqrt(Primes[i])) to 1 by -1 do
if isprime(Primes[i] - k^2) then break fi
od:
if k = 0 then A:= A, Primes[i] fi;
od:
A; # Robert Israel, Sep 03 2014
MATHEMATICA
Do[ k = 1; p = Prime[n]; While[k^2 < p && !PrimeQ[p - k^2], k++ ]; If[k^2 > p, Print[p]], {n, 1, 10^6} ]
Module[{nn=1000, pr}, pr=Flatten[Table[Prime[n]+Range[nn]^2, {n, nn}]]; Complement[Prime[Range[nn]], pr]] (* Harvey P. Dale, May 30 2014 *)
PROG
(PARI) is(p)=forstep(m=2, sqrtint(p), 2, if(isprime(p-m^2), return(0))); isprime(p) && (p==2 || !issquare(p-2)) \\ Charles R Greathouse IV, Jun 04 2012
CROSSREFS
Cf. A000040. Complement of A065376.
Sequence in context: A018012 A359673 A216684 * A215215 A077278 A073683
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Nov 03 2001
EXTENSIONS
Offset corrected by Charles R Greathouse IV, May 29 2012
STATUS
approved