A071855 - OEIS

%I #11 Mar 25 2015 01:21:06

%S 1,37,41,43,47,49,58,65,69,81,85,92,128,130,135,136,154,184,208,220,

%T 228,450,540,840

%N Numbers n such that A067434(n) = A000720(n) + A000005(n).

%C No further terms below 143260.

%C No further terms below 2*10^4. - _Robert G. Wilson v_

%t Select[ Range[10^3], Length[ FactorInteger[ Binomial[2#, # ]]] == PrimePi[ # ] + DivisorSigma[0, # ] & ]

%o (PARI) for(n=1,1000,if(omega(binomial(2*n,n))=sum(i=1,n,isprime(i))+numdiv(n),print1(n,",")))

%K nonn

%O 1,2

%A _Benoit Cloitre_, Jun 09 2002