cp's OEIS Frontend

A354162 Products of exactly two distinct odd primes in A090252, in order of appearance.

%I A354162 #9 Jun 01 2022 02:00:28
%S A354162 21,55,85,57,161,319,217,481,205,731,517,159,1121,1403,871,355,1241,
%T A354162 869,2407,1691,413,3007,2323,1391,4033,565,5207,2227,5891,6533,4321,
%U A354162 453,1007,623,4867,2231,6161,2119,11189,6401,12709,7421,2159,9563,8213,1507,15247,9259,4031,12367,597,2869,11183,1561,13393,7099,3611,14213,24823
%N A354162 Products of exactly two distinct odd primes in A090252, in order of appearance.
%C A354162 Odd terms in A354160. - _Chai Wah Wu_, May 31 2022
%o A354162 (Python)
%o A354162 from itertools import count, islice
%o A354162 from collections import deque
%o A354162 from math import gcd, lcm
%o A354162 from sympy import factorint
%o A354162 def A354162_gen(): # generator of terms
%o A354162     aset, aqueue, c, b, f = {1}, deque([1]), 2, 1, True
%o A354162     while True:
%o A354162         for m in count(c):
%o A354162             if m not in aset and gcd(m,b) == 1:
%o A354162                 if m % 2 and len(fm := factorint(m)) == sum(fm.values()) == 2:
%o A354162                     yield m
%o A354162                 aset.add(m)
%o A354162                 aqueue.append(m)
%o A354162                 if f: aqueue.popleft()
%o A354162                 b = lcm(*aqueue)
%o A354162                 f = not f
%o A354162                 while c in aset:
%o A354162                     c += 1
%o A354162                 break
%o A354162 A354162_list = list(islice(A354162_gen(),25)) # _Chai Wah Wu_, May 31 2022
%Y A354162 Cf. A090252, A354159, A354160, A354161, A354163.
%K A354162 nonn
%O A354162 1,1
%A A354162 _N. J. A. Sloane_, May 30 2022