A091310 Primes not of the form p*q + p - q with prime p and q.

2, 3, 11, 23, 47, 53, 59, 71, 79, 83, 101, 107, 131, 163, 167, 173, 179, 191, 223, 227, 239, 251, 263, 269, 293, 311, 331, 347, 359, 367, 383, 419, 431, 439, 443, 467, 479, 491, 503, 509, 547, 563, 587, 599, 607, 641, 647, 653, 659, 683, 691, 719, 727, 733

Offset: 1

Author

Zak Seidov, Feb 21 2004

Keywords

• nonn

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Primes not in A091301.

Programs

Maple

N:= 1000: # for terms <= N
P:= select(isprime, [2,seq(i,i=3..N,2)]):
nP:= nops(P):
S:= {}:
for i from 1 to nP do
  for j from 1 to nP do
    x:= P[i]*P[j]+P[i]-P[j];
    if x > N then break fi;
    if isprime(x) then S:= S union {x} fi
od od:
sort(convert(convert(P,set) minus S, list)); # Robert Israel, Jun 05 2025

Mathematica

x = Take[ Select[ Union[ Flatten[ Table[ Prime[p]*Prime[q] + Prime[p] - Prime[q], {p, 116}, {q, 116}]]], PrimeQ[ # ] &], 200]; y = Table[ Prime[i], {i, PrimePi[ p[[ -1]] ]}]; Take[ Complement[y, x], 54] (* Robert G. Wilson v *)