cp's OEIS Frontend

A331304 For n <= 4, a(n) = n, for n > 4, if n is prime, a(n) = 3 + 2*A000035(A000720(n)), otherwise a(n) = 3 + n - A000720(n).

%I A331304 #8 Jan 18 2020 18:23:47
%S A331304 1,2,3,4,5,6,3,7,8,9,5,10,3,11,12,13,5,14,3,15,16,17,5,18,19,20,21,22,
%T A331304 3,23,5,24,25,26,27,28,3,29,30,31,5,32,3,33,34,35,5,36,37,38,39,40,3,
%U A331304 41,42,43,44,45,5,46,3,47,48,49,50,51,5,52,53,54,3,55,5,56,57,58,59,60,3,61,62,63,5,64,65,66,67,68,3,69,70,71,72,73,74,75,5,76,77,78,3,79,5,80,81
%N A331304 For n <= 4, a(n) = n, for n > 4, if n is prime, a(n) = 3 + 2*A000035(A000720(n)), otherwise a(n) = 3 + n - A000720(n).
%C A331304 Restricted growth sequence transform of function f defined as: f(n) = A071986(n) when n is an odd prime, otherwise f(n) = -n.
%C A331304 For all i, j:
%C A331304   a(i) = a(j) => A305801(i) = A305801(j),
%C A331304   a(i) = a(j) => A329647(i) = A329647(j),
%C A331304   a(i) = a(j) => A329903(i) = A329903(j).
%H A331304 Antti Karttunen, <a href="/A331304/b331304.txt">Table of n, a(n) for n = 1..100000</a>
%H A331304 <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a>
%F A331304 For n <= 4, a(n) = n, for n > 4, if n is prime, a(n) = 3 + 2*A000035(A000720(n)), otherwise a(n) = 3 + n - A000720(n).
%o A331304 (PARI) A331304(n) = if(n<=4,n,if(isprime(n),3+2*(primepi(n)%2),3+n-primepi(n)));
%Y A331304 Cf. A000720, A071986, A305801, A329647, A329903.
%Y A331304 Cf. also A319704.
%K A331304 nonn
%O A331304 1,2
%A A331304 _Antti Karttunen_, Jan 18 2020