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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 (list; graph; refs; listen; history; text; internal format)
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

LINKS

Table of n, a(n) for n=1..15.

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: A309535 A018012 A216684 * A215215 A077278 A073683

Adjacent sequences:  A065374 A065375 A065376 * A065378 A065379 A065380

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Nov 03 2001

EXTENSIONS

Offset corrected by Charles R Greathouse IV, May 29 2012

STATUS

approved

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Last modified July 6 12:26 EDT 2022. Contains 355110 sequences. (Running on oeis4.)