login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A233933 Smallest number k such that R(n) is the n-th divisor of k, where R(n) is the n-th Ramanujan prime (A104272). 0

%I

%S 11,34,116,246,752,708,4288,1704,3492,4848,11556,7620,28608,47112,

%T 24048,21480,45612,40860,54960,218088,180684,121464,94680,242100,

%U 269760,486288,313488,249840,376920,308280,738540,721800,515340,1106160,930960,935280,737520

%N Smallest number k such that R(n) is the n-th divisor of k, where R(n) is the n-th Ramanujan prime (A104272).

%e a(2) = 11 because the divisors of 11 are {1, 11}, and the 2nd divisor of 11 is 11 = A104272(2);

%e a(3) = 34 because the divisors of 34 are {1, 2, 17, 34}, and the 3rd divisor of 34 is 17 = A104272(3).

%t nn=20; R=Table[0,{nn}]; s=0; Do[If[PrimeQ[k],s++]; If[PrimeQ[k/2],s--]; If[s<nn, R[[s+1]]=k], {k,Prime[3*nn]}]; R=R+1; t=Table[0,{nn}]; found=1; n=2; While[found < nn, n++; d=Divisors[n]; Do[If[i <= nn && d[[i]] == Part[R,i] && t[[i]]==0, t[[i]]=n; found++], {i, Length[d]}]]; Rest[t] (* Program from _T. D. Noe_ adapted for this sequence - see A104272 and A221647 *)

%Y Cf. A104272, A221647.

%K nonn

%O 2,1

%A _Michel Lagneau_, Dec 18 2013

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 15 16:12 EDT 2019. Contains 327078 sequences. (Running on oeis4.)