A354203 - OEIS

%I #5 May 23 2022 17:45:49

%S 1,1,1,1,2,1,3,1,1,2,7,1,5,3,2,1,13,1,11,2,3,7,19,1,4,5,1,3,17,2,23,1,

%T 7,13,6,1,29,11,5,2,37,3,31,7,2,19,43,1,9,4,13,5,41,1,14,3,11,17,47,2,

%U 53,23,3,1,10,7,59,13,19,6,67,1,61,29,4,11,21,5,71,2,1,37,79,3,26,31,17,7,73,2,15,19,23

%N Fully multiplicative with a(p^e) = A354201(A000720(p))^e.

%H <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a>

%o (PARI)

%o A354201(n) = if(n<=3,(n+1)\2,my(m=prime(n)%4); forstep(i=n-1,0,-1,if(m==(prime(i)%4),return(prime(i)))));

%o A354203(n) = { my(f=factor(n)); for(k=1,#f~,f[k,1] = A354201(primepi(f[k,1]))); factorback(f); };

%Y Left inverse of A354202.

%Y Cf. A354201, A354206.

%K nonn,mult

%O 1,5

%A _Antti Karttunen_, May 23 2022