cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A346207 Numbers k such that k and k+1 are products of at least 6 primes.

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%I A346207 #12 Jul 11 2021 03:25:24
%S A346207 1215,3968,5103,5264,6560,7424,7695,8991,9375,9800,11024,11583,11744,
%T A346207 12375,12879,13040,14175,14336,14624,15624,16064,16280,16767,16928,
%U A346207 17199,17576,18224,21375,21735,22112,22599,22815,23408,24255,24543,24704,24975,25839,26000,26487,27135
%N A346207 Numbers k such that k and k+1 are products of at least 6 primes.
%C A346207 Integers k such that k and k+1 are in A046305.
%e A346207 1215 = 3^5*5 is a product of 6 primes. The next integer, 1216 = 2^6*19, is a product of 7 primes. Thus, 1215 is in this sequence.
%p A346207 q:= n-> andmap(x-> numtheory[bigomega](x)>5, [n, n+1]):
%p A346207 select(q, [$1..30000])[];  # _Alois P. Heinz_, Jul 10 2021
%t A346207 Select[Range[100000], Total[Transpose[FactorInteger[#]][[2]]] >= 6 && Total[Transpose[FactorInteger[# + 1]][[2]]] >= 6 &]
%o A346207 (Python)
%o A346207 from sympy import factorint
%o A346207 def prod6(n): return sum(factorint(n).values()) >= 6
%o A346207 def aupto(lim): return [k for k in range(lim+1) if prod6(k) and prod6(k+1)]
%o A346207 print(aupto(27135)) # _Michael S. Branicky_, Jul 10 2021
%o A346207 (PARI) isA346207(k) = (bigomega(k) >= 6) && (bigomega(k+1) >= 6) \\ _Jianing Song_, Jul 10 2021
%Y A346207 Cf. A046305, A345744.
%K A346207 nonn
%O A346207 1,1
%A A346207 _Tanya Khovanova_, Jul 10 2021