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A350095 a(n) is the smaller of 2 consecutive primes bounding an interval containing a record number A350097(n) of odd squarefree semiprimes (A046388). 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..31.

FORMULA

A350096(n) = nextprime(a(n)).

EXAMPLE

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).

CROSSREFS

A350096 are the upper ends of the intervals, A350097 are the corresponding counts of odd squarefree semiprimes in the intervals.

Cf. A000101, A005250, A046388.

Sequence in context: A335732 A342706 A095379 * A160772 A271575 A039403

Adjacent sequences:  A350092 A350093 A350094 * A350096 A350097 A350098

KEYWORD

nonn

AUTHOR

Hugo Pfoertner, Dec 25 2021

EXTENSIONS

a(29)-a(31) from Martin Ehrenstein, Dec 28 2021

STATUS

approved

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Last modified August 13 14:01 EDT 2022. Contains 356091 sequences. (Running on oeis4.)