A370008 a(n) is the greatest prime less than 3*prime(n).

5, 7, 13, 19, 31, 37, 47, 53, 67, 83, 89, 109, 113, 127, 139, 157, 173, 181, 199, 211, 211, 233, 241, 263, 283, 293, 307, 317, 317, 337, 379, 389, 409, 409, 443, 449, 467, 487, 499, 509, 523, 541, 571, 577, 587, 593, 631, 661, 677, 683, 691, 709, 719, 751

Offset

1,1

Links

Table of n, a(n) for n=1..54.

Example

5 < 3*2 < 7 < 3*3 < 11 < 13 < 3*5, so (a(1), a(2), a(3)) = (5,7,13).

Mathematica

Table[Prime[PrimePi[3*Prime[n]]], {n, 1, 200}]

Prog

(PARI) a(n) = precprime(3*prime(n)); \\ Michel Marcus, Feb 10 2024

Crossrefs

Cf. A000040, A001748, A059786, A059788, A370009.

Sequence in context: A099349 A167464 A280266 * A243457 A189441 A106986

Adjacent sequences: A370005 A370006 A370007 * A370009 A370010 A370011

Keyword

nonn

Author

Clark Kimberling, Feb 09 2024

Status

approved