A368732 Primes whose index is one, another prime number, or a semiprime.

2, 3, 5, 7, 11, 13, 17, 23, 29, 31, 41, 43, 47, 59, 67, 73, 79, 83, 97, 101, 109, 127, 137, 139, 149, 157, 163, 167, 179, 191, 199, 211, 227, 233, 241, 257, 269, 271, 277, 283, 293, 313, 331, 347, 353, 367, 373, 389, 401, 421, 431, 439, 443, 449, 461, 467, 487

Offset

1,1

Links

Table of n, a(n) for n=1..57.

Mathematica

Prime/@Select[Range[100], PrimeOmega[#]<=2&]

Crossrefs

For just primes we have A006450, products A076610, strict A302590.

These indices are A037143.

For just semiprimes we have A106349, products A339112, strict A340020.

Products of these primes are A368728, odd A368729, odd strict A340019.

Products of the complementary primes are A368833.

A000607 counts partitions into primes, with ones allowed A034891.

A001358 lists semiprimes, squarefree A006881.

A056239 adds up prime indices, row sums of A112798.

A101048 counts partitions into semiprimes.

A322551 lists primes of squarefree semiprime index.

Cf. A000040, A000720, A001222, A003963, A005117, A302242, A309356, A320628, A320911, A320912, A339113.

Sequence in context: A194954 A344384 A299956 * A192503 A040067 A181659

Adjacent sequences: A368729 A368730 A368731 * A368733 A368734 A368735

Keyword

nonn

Author

Gus Wiseman, Jan 08 2024

Status

approved