cp's OEIS Frontend

A286361 Least number with the same prime signature as {the largest divisor of n with only prime factors of the form 4k+1} has: a(n) = A046523(A170818(n)).

%I A286361 #14 May 09 2017 14:26:53
%S A286361 1,1,1,1,2,1,1,1,1,2,1,1,2,1,2,1,2,1,1,2,1,1,1,1,4,2,1,1,2,2,1,1,1,2,
%T A286361 2,1,2,1,2,2,2,1,1,1,2,1,1,1,1,4,2,2,2,1,2,1,1,2,1,2,2,1,1,1,6,1,1,2,
%U A286361 1,2,1,1,2,2,4,1,1,2,1,2,1,2,1,1,6,1,2,1,2,2,2,1,1,1,2,1,2,1,1,4,2,2,1,2,2,2,1,1,2,2,2,1,2,1,2,2,2,1,2,2
%N A286361 Least number with the same prime signature as {the largest divisor of n with only prime factors of the form 4k+1} has: a(n) = A046523(A170818(n)).
%H A286361 Antti Karttunen, <a href="/A286361/b286361.txt">Table of n, a(n) for n = 1..10000</a>
%F A286361 a(n) = A046523(A170818(n)).
%F A286361 a(n) = A286363(A267099(n)).
%o A286361 (Scheme) (define (A286361 n) (A046523 (A170818 n)))
%o A286361 (Python)
%o A286361 from sympy import factorint
%o A286361 from operator import mul
%o A286361 def P(n):
%o A286361     f = factorint(n)
%o A286361     return sorted([f[i] for i in f])
%o A286361 def a046523(n):
%o A286361     x=1
%o A286361     while True:
%o A286361         if P(n) == P(x): return x
%o A286361         else: x+=1
%o A286361 def a072438(n):
%o A286361     f = factorint(n)
%o A286361     return 1 if n == 1 else reduce(mul, [1 if i%4==1 else i**f[i] for i in f])
%o A286361 def a(n): return a046523(n/a072438(n)) # _Indranil Ghosh_, May 09 2017
%Y A286361 Cf. A046523, A170818, A267099, A267113, A286363, A286364, A286365.
%Y A286361 Differs from A063014 for the first time at n=25, where a(25) = 4, while A063014(25) = 3.
%K A286361 nonn
%O A286361 1,5
%A A286361 _Antti Karttunen_, May 08 2017