A136153 Composites one larger than a prime, with exactly four distinct prime factors.

390, 420, 462, 510, 570, 660, 770, 798, 840, 858, 930, 1020, 1050, 1092, 1110, 1218, 1230, 1260, 1290, 1302, 1320, 1410, 1428, 1430, 1482, 1554, 1560, 1610, 1638, 1710, 1722, 1848, 1890, 1914, 1932, 1950, 1974, 1980, 2030, 2040, 2070, 2090, 2100, 2130

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..2000

Formula

Equals A008864 INTERSECT A033993. - R. J. Mathar, Feb 20 2008

Example

a(0)=390 because 30 follows the prime 29 and has four prime factors 2, 3, 5 and 13.

Mathematica

Select[Prime[Range[400]]+1, PrimeNu[#]==4&] (* Harvey P. Dale, Aug 15 2021 *)

Prog

(PARI) isok(n) = (omega(n)==4) && isprime(n-1); \\ Michel Marcus, Jun 08 2014

Crossrefs

Cf. A136151, A136152, A136154, A136155.

Sequence in context: A300340 A228580 A242182 * A069477 A325993 A108573

Adjacent sequences: A136150 A136151 A136152 * A136154 A136155 A136156

Keyword

easy,nonn

Author

Enoch Haga, Dec 16 2007

Extensions

Edited by R. J. Mathar, Feb 20 2008

Status

approved