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.
%I A321502 #4 Dec 03 2018 21:36:37 %S A321502 65,69,77,84,90,104,105,110,114,119,129,132,140,153,154,155,164,165, %T A321502 170,174,182,185,186,189,194,195,203,204,209,219,220,221,230,231,234, %U A321502 237,245,246,252,254,258,259,260,264,265,266,272,273,275,279,284,285,286,290,294,299,300,305 %N A321502 Numbers m such that m and m+1 have at least 2, but m or m+1 has at least 3 prime divisors. %C A321502 Since m and m+1 cannot have a common factor, m(m+1) has at least 2+3 prime divisors (= distinct prime factors), whence m+1 > sqrt(primorial(5)) ~ 48. It turns out that a(1)*(a(1)+1) = 2*3*5*11*13, i.e., the prime factor 7 is not present. %F A321502 Equals A255346 \ A074851. %o A321502 (PARI) select( is_A321502(n)=vecmax(n=[omega(n), omega(n+1)])>2&&vecmin(n)>1, [1..500]) %Y A321502 Cf. A321493, A321494, A321495, A321496, A321497 (analog for k = 3, ..., 7 prime divisors). %Y A321502 Cf. A074851, A140077, A140078, A140079 (m and m+1 have exactly k = 2, 3, 4, 5 prime divisors). %Y A321502 Cf. A255346, A321503 .. A321506, A321489 (m and m+1 have at least 2, ..., 7 prime divisors). %Y A321502 Cf. A006049, A006549, A093548. %K A321502 nonn %O A321502 1,1 %A A321502 _M. F. Hasler_, Nov 27 2018