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A063968 Numbers k such that sopf(k) = sopf(k+2), where sopf(k) = A008472(k).

%I A063968 #21 Nov 19 2019 06:00:46
%S A063968 2,340,845,950,1340,3724,5694,6102,7657,8991,9331,9709,10323,11388,
%T A063968 11390,12460,15870,18912,19778,20882,21715,24732,26978,29052,29632,
%U A063968 32428,33596,35028,38178,42718,43068,45750,46102,50396,53251,61408
%N A063968 Numbers k such that sopf(k) = sopf(k+2), where sopf(k) = A008472(k).
%H A063968 Amiram Eldar, <a href="/A063968/b063968.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from Harry J. Smith)
%o A063968 (PARI) sopf(n,s,fac,i)=fac=factor(n); for(i=1,matsize(fac)[1],s=s+fac[i,1]); return(s);
%o A063968 j=[]; for(n=1,100000, if(sopf(n)==sopf(n+2),j=concat(j,n))); j
%o A063968 (PARI) sopf(n)= { local(f,s=0); f=factor(n); for(i=1, matsize(f)[1], s+=f[i, 1]); return(s) }
%o A063968 { n=0; r=sopf(1); s=sopf(2); for (m=1, 10^9, t=sopf(m + 2); if(r==t, write("b063968.txt", n++, " ", m); if (n==1000, break)); r=s; s=t ) } \\ _Harry J. Smith_, Sep 04 2009
%Y A063968 Cf. A008472, A006145.
%K A063968 nonn
%O A063968 1,1
%A A063968 _Jason Earls_, Sep 05 2001