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 A372781 #29 Jul 06 2024 14:01:05 %S A372781 7,11,13,19,23,29,31,37,41,43,47,49,53,59,61,67,71,73,77,79,83,89,93, %T A372781 97,101,103,107,109,113,121,127,129,131,137,139,143,149,151,155,157, %U A372781 161,163,167,169,173,179,181,183,191,193,197,199,201,203,209,211,213,215,217,223 %N A372781 Odd numbers k such that A001221(k) < A001221(A003958(k)). %e A372781 31 is in the sequence because 31 = 31^1, so omega(31) = 1, but (31 - 1)^1 = 30^1 = 2^1 * 3^1 * 5^1, so omega(30) = 3, and 1 < 3. %p A372781 q:= n-> (f-> n::odd and f(n)<f(mul((i[1]-1)^i[2], %p A372781 i=ifactors(n)[2])))(k-> nops(ifactors(k)[2])): %p A372781 select(q, [$1..333])[]; # _Alois P. Heinz_, Jul 04 2024 %t A372781 f[p_, e_] := (p - 1)^e; s[n_] := Times @@ f @@@ FactorInteger[n]; Select[Range[3, 1000, 2], PrimeNu[#] < PrimeNu[s[#]] &] (* _Amiram Eldar_, Jul 04 2024 *) %Y A372781 Cf. A001221, A003958, A005408, A138889. %K A372781 nonn %O A372781 1,1 %A A372781 _Mike Jones_, Jul 04 2024