login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Squarefree numbers of the form (prime(n)+1)*(prime(n+1)+1)/4.
3

%I #9 Jul 13 2013 12:02:55

%S 3,6,42,399,462,930,1054,3135,4830,6478,13110,19599,20022,24963,26394,

%T 35530,38805,39999,41205,44310,52899,71002,74254,81510,94863,95790,

%U 103362,109230,111547,114243,135790,144399,146685,157206,166866,183183

%N Squarefree numbers of the form (prime(n)+1)*(prime(n+1)+1)/4.

%C Subsequence of A079079; A008966(a(n)) = 1.

%H Reinhard Zumkeller, <a href="/A079095/b079095.txt">Table of n, a(n) for n = 1..10000</a>

%e (A000040(12)+1)*(A000040(12+1)+1)/4 = (37+1)*(41+1)/4 = 399 = 3*7*19, therefore 399 is a term.

%o (Haskell)

%o a079095 n = a079095_list !! (n-1)

%o a079095_list = filter ((== 1) . a008966) a079079_list

%o -- _Reinhard Zumkeller_, Oct 09 2012

%Y Cf. A079093, A005117.

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Dec 22 2002