cp's OEIS Frontend

A361470 a(n) = gcd(n+1, A135504(n)).

%I A361470 #14 May 11 2023 09:23:04
%S A361470 1,3,2,1,6,1,8,9,2,1,12,1,14,3,16,1,18,1,20,21,2,1,24,5,2,27,28,1,30,
%T A361470 1,32,3,2,35,36,1,38,3,40,1,42,1,44,45,2,1,48,49,50,3,4,1,54,55,56,57,
%U A361470 2,1,60,1,62,63,64,5,66,1,68,3,70,1,72,1,74,75,76,77,6,1,80,81,2,1,84,85,2,3,88
%N A361470 a(n) = gcd(n+1, A135504(n)).
%H A361470 Michael De Vlieger, <a href="/A361470/b361470.txt">Table of n, a(n) for n = 1..10000</a>
%F A361470 a(n) = (n+1) / A135506(n).
%t A361470 MapIndexed[GCD[First[#2] + 1, #1] &, RecurrenceTable[{a[1] == 1, a[n] == a[n - 1] + LCM[a[n - 1], n]}, a, {n, 87}] ] (* _Michael De Vlieger_, May 11 2023 *)
%o A361470 (PARI)
%o A361470 up_to = 65537;
%o A361470 A361470list(up_to_n) = { my(v=vector(up_to), x1=1, x2); for(n=2, 1+up_to_n, x2 = x1+lcm(x1, n); v[n-1] = gcd(x1,n); x1=x2); (v); };
%o A361470 v361470 = A361470list(up_to);
%o A361470 A361470(n) = v361470[n];
%o A361470 (Python)
%o A361470 from math import gcd
%o A361470 from itertools import count, islice
%o A361470 def A361470_gen(): # generator of terms
%o A361470     x = 1
%o A361470     for n in count(2):
%o A361470         yield (y:=gcd(x,n))
%o A361470         x += x*n//y
%o A361470 A361470_list = list(islice(A361470_gen(),20)) # _Chai Wah Wu_, May 11 2023
%Y A361470 Cf. A135504, A135506.
%K A361470 nonn
%O A361470 1,2
%A A361470 _Antti Karttunen_, Mar 26 2023