login
Inverse permutation to sequence A083872.
1

%I #11 Nov 08 2018 21:10:41

%S 1,2,3,5,9,4,31,6,17,10,271,7,793,32,11,18,5377,19,14689,12,33,272,

%T 96001,8,161,794,97,34,917281,13,2332801,61,273,5378,35,20,19595521,

%U 14690,795,14,102435841,36,258048001,274,21,96002,1258709761,22,1585,162,5379

%N Inverse permutation to sequence A083872.

%H Rémy Sigrist, <a href="/A119628/b119628.txt">Table of n, a(n) for n = 1..10000</a>

%F a(p) = A027423(p-1) + 1 for any prime number p. - _Rémy Sigrist_, Nov 08 2018

%o (PARI) {m=31;v=[];for(n=1,m,v=concat(v,vecsort(eval(setminus(Set(divisors(n!)),Set(v))))));z=100;u=vector(z);for(j=1,#v,if(v[j]<=z,u[v[j]]=j));i=1;while(u[i]>0,print1(u[i],",");i++)} \\ Klaus Brockhaus, Aug 16 2006

%o (PARI) a(n) = my (ff=1, f=1); for (i=1, oo, f*=i; if (f%n==0, return (numdiv(ff) + sum(j=1, n, ff%j!=0 && f%j == 0))); ff=f) \\ _Rémy Sigrist_, Nov 08 2018

%Y Cf. A027423, A083872.

%K nonn

%O 1,2

%A _Leroy Quet_, Jun 08 2006

%E a(11) to a(36) from _Klaus Brockhaus_, Aug 16 2006

%E More terms from _Rémy Sigrist_, Nov 08 2018