A350095 a(n) is the smaller of 2 consecutive primes bounding an interval containing a record number A350097(n) of odd squarefree semiprimes (A046388).
13, 31, 89, 199, 211, 887, 1129, 1327, 9973, 15683, 19609, 44293, 155921, 370261, 396733, 492113, 1357201, 1671781, 3826019, 17836409, 20831323, 47465267, 107534587, 122164747, 434865437, 436273009, 2300942549, 4302407359, 10726904659, 25056082087, 42652618343
Offset: 1
Keywords
Examples
a(1) = 13: semiprime 15 < 17 = nextprime(a(1)) = A350096(1); a(2) = 31: semiprimes 33, 35 < 37 = A350096(2); a(6) = 887: semiprimes 889, 893, 895, 899, 901, 905 < 907 = A350096(6); a(7) = 1129: semiprimes 1133, 1135, 1137, 1139, 1141, 1145, 1147, 1149 < 1151 = A350096(7); a(8) = 1327: semiprimes 1329, 1333, 1337, 1339, 1343, 1345, 1347, 1349, 1351, 1355, 1357 < 1361 = A350096(8).
Links
- Lucas A. Brown, Table of n, a(n) for n = 1..32 (terms 1-28 from _Hugo Pfoertner_, 29-31 from _Martin Ehrenstein_)
- Lucas A. Brown, Python program.
Crossrefs
Formula
A350096(n) = nextprime(a(n)).
Extensions
a(29)-a(31) from Martin Ehrenstein, Dec 28 2021
a(32) from Lucas A. Brown, Mar 21 2024