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 A106799 #16 Jan 16 2022 09:18:53 %S A106799 0,0,0,0,1,0,1,0,0,1,1,0,1,1,1,0,1,0,1,1,1,1,1,0,2,1,0,1,1,1,1,0,1,1, %T A106799 2,0,1,1,1,1,1,1,1,1,1,1,1,0,2,2,1,1,1,0,2,1,1,1,1,1,1,1,1,0,2,1,1,1, %U A106799 1,2,1,0,1,1,2,1,2,1,1,1,0,1,1,1,2,1,1,1,1,1,2,1,1,1,2,0,1,2,1,2,1,1,1,1,2 %N A106799 Number of prime factors of n apart from 2 or 3, counted with multiplicity. %C A106799 Self-similar in every second and in every third term, i.e., a(n) = a(2n) = a(3n). %C A106799 Logarithmic since a(b*c) = a(b) + a(c). %C A106799 Coincidentally, a(n) = A101040(n+78) for 1 < n < 20. %H A106799 Reinhard Zumkeller, <a href="/A106799/b106799.txt">Table of n, a(n) for n = 1..10000</a> %F A106799 a(n) = A001222(n) - A007814(n) - A007949(n) = A087436(n) - A007949(n). %F A106799 a(n) = A001222(A065330(n)). - _Reinhard Zumkeller_, May 19 2005 %e A106799 a(24) = 0 since 24 = 2*2*2*3. %e A106799 a(25) = 2 since 25 = 5*5. %e A106799 a(26) = 1 since 26 = 2*13. %t A106799 a[n_] := PrimeOmega[n] - IntegerExponent[n, 2] - IntegerExponent[n, 3]; Array[a, 100] (* _Amiram Eldar_, Jan 16 2022 *) %o A106799 (Haskell) %o A106799 a106799 = a001222 . a065330 -- _Reinhard Zumkeller_, Nov 19 2015 %o A106799 (PARI) a(n) = bigomega(n) - valuation(n, 2) - valuation(n, 3); \\ _Michel Marcus_, Jan 16 2022 %Y A106799 Cf. A001222, A007814, A007949, A027746, A065330, A087436, A101040, A169611. %K A106799 nonn %O A106799 1,25 %A A106799 _Henry Bottomley_, May 17 2005