Primes having numbers with 2 and 4 prime factors (counting multiplicity) before or after them.
23, 37, 59, 61, 83, 157, 227, 277, 347, 563, 733, 877, 997, 1213, 1237, 1283, 1307, 1523, 2797, 3253, 3517, 3733, 3803, 4547, 5387, 5483, 6037, 6827, 7187, 7213, 7933, 9013, 9133, 9277, 10357, 10883, 12107, 12157, 12227, 12757, 13043, 13093, 13163, 14243
1
This sequence is the union of the previous two sequences.
T. D. Noe, Plot of 1000 terms
T. D. Noe, Table of 1000 terms
MathOverflow, Are there infinitely many primes p such that both p-1 and p+1 have at most 3 prime factors, counted with multiplicity?
(Mma) Select[Prime[Range[2, 1000000]], (Plus @@ Transpose[FactorInteger[# - 1]][[2]] == 4 && Plus @@ Transpose[FactorInteger[# + 1]][[2]] == 2) || (Plus @@ Transpose[FactorInteger[# - 1]][[2]] == 2 && Plus @@ Transpose[FactorInteger[# + 1]][[2]] == 4) &, 100]
Cf. A079153, A106639, S000327-S000330.
nonn
T. D. Noe, Nov 12 2014