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Difference between the smallest semiperimeter (see A063655) and its integer log (A001414) equals 1.
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%I #3 Sep 24 2013 00:41:41

%S 2,3,5,7,11,13,17,18,19,23,24,29,30,31,37,41,42,43,47,53,59,61,66,67,

%T 71,73,78,79,83,89,97,101,102,103,107,109,113,114,127,131,137,138,139,

%U 149,151,157,163,167,173,174,179,181,186,191,193,197,199,211,222,223,227

%N Difference between the smallest semiperimeter (see A063655) and its integer log (A001414) equals 1.

%C Theorem: Except for 24, the sequence is the union of primes and 6*primes.

%e Any prime p, since it has semiperimeter p+1 and its integer log is p.

%t logint = Function[n, Module[{vn}, vn = Transpose[FactorInteger[n]];vn[[1]].vn[[2]] ]]; semiperi = Function[n, Min[Divisors[n] + Reverse[Divisors[n]]]]; sq = {}; Do[If[semiperi[k] == logint[k] + 1, AppendTo[sq, k]], {k, 2, 500}]; sq

%Y Cf. A001414 and A063655.

%K nonn

%O 0,1

%A _Carlos Alves_, Dec 31 2004