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 A289553 #17 Jul 02 2025 19:28:31 %S A289553 1,4,8,9,12,16,18,20,24,25,27,28,30,32,36,40,42,44,45,48,49,50,52,54, %T A289553 56,60,63,64,66,68,70,72,75,76,78,80,81,84,88,90,92,96,98,99,100,102, %U A289553 104,105,108,110,112,114,116,117,120,121,124,125,126,128,130,132 %N A289553 Numbers that are not the product of two distinct noncomposite numbers (A008578). %C A289553 Numbers k such that tau(k) = A000005(k) is not equal to 2*omega(k) = 2*A001221(k). %e A289553 Number 6 is not in the sequence because 6 = 2 * 3. %o A289553 (Magma) [n: n in [1..1000] | NumberOfDivisors(n) ne 2*#PrimeDivisors(n)]; %Y A289553 Complement of A167171. %Y A289553 Cf. A246716 (with two distinct primes), A008578 (with two distinct nonprimes), A289555 (with two distinct composites). %K A289553 nonn %O A289553 1,2 %A A289553 _Jaroslav Krizek_, Jul 07 2017