A350420 Primes p such that p*q+q-p is a semiprime, where q is the next prime after p.

11, 29, 41, 47, 53, 59, 73, 101, 107, 131, 139, 151, 173, 181, 197, 199, 211, 257, 271, 311, 317, 331, 373, 389, 401, 461, 467, 479, 491, 509, 521, 523, 541, 563, 593, 599, 601, 607, 619, 647, 677, 719, 727, 743, 751, 809, 827, 919, 929, 947, 971, 977, 1013, 1019, 1021, 1033, 1049, 1061, 1063

Offset

1,1

Links

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

Example

a(3) = 41 is a term because it is prime, the next prime is 43, and 41*43 + 43 - 41 = 1765 = 5*363 is a semiprime.

Maple

q:= 2: R:= NULL: count:= 0:
while count < 100 do
p:= q; q:= nextprime(q);
s:= p*q+q-p;
if numtheory:-bigomega(s)=2 then
  count:= count+1; R:= R, p;
fi
od:
R;

Crossrefs

Cf. A001358, A138170.

Sequence in context: A279775 A211191 A353043 * A240678 A087693 A106017

Adjacent sequences: A350417 A350418 A350419 * A350421 A350422 A350423

Keyword

nonn

Author

J. M. Bergot and Robert Israel, Dec 30 2021

Status

approved