A335346 Lesser of two consecutive semiprimes whose sum and difference are also semiprimes.

51, 65, 87, 111, 129, 146, 209, 249, 278, 291, 305, 335, 377, 407, 447, 485, 489, 497, 629, 681, 699, 749, 767, 785, 917, 939, 951, 989, 1007, 1018, 1037, 1115, 1177, 1191, 1257, 1397, 1457, 1469, 1497, 1509, 1546, 1565, 1594, 1707, 1731, 1757, 1799, 1945, 1977

Offset

1,1

Comments

Intersection of A272306 and A272307.

Links

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

Example

51 = A272306(8) = A272307(3), 65 = A272306(10) = A272307(5).

Maple

b:= 4:
Res:= NULL: count:= 0:
while count < 100 do
  a:= b;
  for k from b+1 do if numtheory:-bigomega(k) = 2  then b:= k; break fi od:
  if numtheory:-bigomega(b-a) = 2 and numtheory:-bigomega(b+a) = 2 then
    count:= count+1; Res:= Res, a;
  fi
od:
Res; # Robert Israel, Nov 10 2022

Prog

(PARI) psp=4; for(k=6, 2000, if(bigomega(k)==2, if(bigomega(k-psp)==2, if(bigomega(k+psp)==2, print1(psp, ", "))); psp=k)) \\ Hugo Pfoertner, Jun 03 2020

Crossrefs

Cf. A001358, A272306, A272307, A272308, A272309.

Sequence in context: A206525 A216055 A034819 * A118147 A015863 A232105

Adjacent sequences: A335343 A335344 A335345 * A335347 A335348 A335349

Keyword

nonn

Author

Zak Seidov, Jun 02 2020

Status

approved