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”).

Smallest square k such that k-1 is a squarefree number with n prime divisors.
1

%I #11 Nov 03 2014 01:13:36

%S 4,16,196,1156,64516,440896,26173456,340254916,14809429636,

%T 787326134596,56199671262736,3984666393117796,468395620836767716,

%U 9526636662047700196,659973251187594258916,205358215375529739638116

%N Smallest square k such that k-1 is a squarefree number with n prime divisors.

%C Program for generating a(n) for large values of n is given is A088028.

%e a(4) = 1156 = 34^2 = 3*5*7*11 +1.

%o (PARI) a(n) = {i = 1; k = i^2; while (! issquarefree(k-1) || (omega(k-1) != n), i++; k = i^2;); k;} \\ _Michel Marcus_, Apr 11 2014

%Y Cf. A088028.

%K nonn

%O 1,1

%A _Amarnath Murthy_, Sep 19 2003

%E More terms from _Ray Chandler_, Oct 04 2003

%E Additional terms from _Thomas Baruchel_, Oct 11 2003