cp's OEIS Frontend

A192015 Arithmetic derivative of prime powers: a(n) = A003415(A000961(n)).

%I A192015 #25 Feb 16 2025 08:33:15
%S A192015 0,1,1,4,1,1,12,6,1,1,32,1,1,1,10,27,1,1,80,1,1,1,1,14,1,1,1,192,1,1,
%T A192015 1,1,108,1,1,1,1,1,1,1,1,22,75,1,448,1,1,1,1,1,1,1,1,26,1,1,1,1,1,1,1,
%U A192015 1,1,1,1,1,1,1,405,1,1024,1,1,1,1,1,1,1,34
%N A192015 Arithmetic derivative of prime powers: a(n) = A003415(A000961(n)).
%C A192015 a(A000040(n)) = 1; a(A002808(n)) > 1;
%C A192015 A001787, A027471, A100484, A079705 and A051674 are subsequences;
%C A192015 A001787 and A024622 give record values and where they occur;
%C A192015 A192016(n) = A003415(a(n)).
%H A192015 Reinhard Zumkeller, <a href="/A192015/b192015.txt">Table of n, a(n) for n = 1..10000</a>
%H A192015 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PrimePower.html">Prime Power</a>
%F A192015 a(n) = A025474(n) * A025473(n)^(A025474(n) - 1).
%t A192015 Join[{0}, Reap[For[n = 1, n <= 300, n++, f = FactorInteger[n]; If[Length[f] == 1, Sow[n*Total[Apply[#2/#1&, f, {1}]]]]]][[2, 1]]] (* _Jean-François Alcover_, Feb 21 2014 *)
%o A192015 (Haskell)
%o A192015 a192015 = a003415 . a000961  -- _Reinhard Zumkeller_, Apr 16 2014
%o A192015 (Python)
%o A192015 from sympy import primepi, integer_nthroot, factorint
%o A192015 def A192015(n):
%o A192015     if n == 1: return 0
%o A192015     def f(x): return int(n+x-1-sum(primepi(integer_nthroot(x,k)[0]) for k in range(1,x.bit_length())))
%o A192015     m, k = n, f(n)
%o A192015     while m != k:
%o A192015         m, k = k, f(k)
%o A192015     return sum((m*e//p for p,e in factorint(m).items())) # _Chai Wah Wu_, Aug 15 2024
%K A192015 nonn
%O A192015 1,4
%A A192015 _Reinhard Zumkeller_, Jun 26 2011