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%I #7 Mar 05 2019 18:19:36
%S 1,2,3,4,5,1,9,8,7,5,5,3,25,6,27,16,11,7,21,10,35,5,15,2,49,50,75,36,
%T 125,9,81,32,13,11,11,1,55,7,63,4,77,35,35,5,175,5,9,12,121,98,49,100,
%U 245,25,225,24,343,125,125,27,625,54,243,64,17,13,39,11,65,11,33,7,13,55,55,3,275,21,189,40,143,77,77,5,385,35,105,1,539
%N a(n) = A017666(A005940(1+n)), where A005940 is the Doudna sequence and A017666(n) = n/gcd(n,sigma(n)).
%H Antti Karttunen, <a href="/A324395/b324395.txt">Table of n, a(n) for n = 0..16500</a>
%H Antti Karttunen, <a href="/A324395/a324395.txt">Data supplement: n, a(n) computed for n = 0..65537</a>
%H <a href="/index/Bi#binary">Index entries for sequences related to binary expansion of n</a>
%H <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%F a(n) = A017666(A005940(1+n)) = A005940(1+n) / A324394(n).
%o (PARI) A324395(n) = { my(m1=1,m2=1,p=2,mp=p*p); while(n, if(!(n%2), p=nextprime(1+p); mp = p*p, m1 *= p; if(3==(n%4),mp *= p,m2 *= (mp-1)/(p-1))); n>>=1); m1/gcd(m1,m2); };
%o (PARI)
%o A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); t }; \\ From A005940
%o A017666(n) = (n/gcd(n, sigma(n)));
%o A324395(n) = A017666(A005940(1+n));
%Y Cf. A005940, A017666, A324054, A324055, A324058, A324349, A324394.
%K nonn
%O 0,2
%A _Antti Karttunen_, Mar 05 2019
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