A064465 - OEIS

%I #16 Jun 24 2018 09:01:27

%S 5,7,13,16,19,31,36,40,41,43,49,50,53,61,74,82,84,89,92,94,102,103,

%T 107,109,113,130,138,140,149,151,154,158,169,181,182,197,199,217,229,

%U 233,239,241,243,257,266,271,293,331,349,361,383,389,409,419,421,439,463

%N Numbers k such that A048138(k) = A034444(k).

%H Harry J. Smith, <a href="/A064465/b064465.txt">Table of n, a(n) for n = 1..100</a>

%o (PARI) f(n) = s=0; for(x=1,n^2, if(sigma(x)-x-1==n,s++)); s ud(n) = 2^omega(n); j=[]; for(n=1,150, if(f(n)==ud(n),j=concat(j,n))); j

%o (PARI) f(n)= { local(s=0); for(x=1, n^2, if(sigma(x) - x - 1==n, s++)); return(s) } ud(n)= { 2^omega(n) } { n=0; for (m=1, 10^9, if (f(m)==ud(m), write("b064465.txt", n++, " ", m); if (n==100, break)) ) } \\ _Harry J. Smith_, Sep 15 2009

%Y Cf. A034444, A048138.

%K easy,nonn

%O 1,1

%A _Jason Earls_, Oct 03 2001

%E More terms from _Klaus Brockhaus_, Oct 03 2001