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Smallest odd number k such that p(2m)-2p(m)=k has exactly n solutions (where p(m) = m-th prime).
2

%I #6 Oct 15 2013 22:31:17

%S 23,1,19,15,209,433,657,135,435,2715,9525,9639,20757,20493,4389,47025,

%T 27555,193875,162435,51405,811497,764547,832995,811485,811515,193755,

%U 1233309,811473,15680805,4247325,10797675,12945345,15391761

%N Smallest odd number k such that p(2m)-2p(m)=k has exactly n solutions (where p(m) = m-th prime).

%e n=0: 23 is the smallest odd number without solutions: see A070774. For n=1, .., 8 the solutions are s1={3}, s2={41, 47}, s3={19, 23, 37}, s4={661, 769, 787, 811}, s5={1619, 1667, 1709, 1823, 1979}, s6={2777, 2843, 2851, 2861, 2897, 3251}, s7={439, 443, 449, 457, 487, 557, 593}, s8={1621, 1637, 1699, 1723, 1741, 1777, 1811, 1987}, expressed in terms of p(x) primes; either values of x and 2x indices or p(2x) are further computable. Odd numbers a(n) forming sequence corresponds to values of p(2x)-2p(x). E.g. p[2*Pi[s4]]=p[2x]={1531, 1747, 1783, 1831} and p[2x]-2p[x]]={209, 209, 209, 209} gives a(4)=209.

%Y Cf. A066066, A022457, A070773, A070774.

%K nonn

%O 0,1

%A _Labos Elemer_, May 06 2002

%E a(15)-a(32) from _Donovan Johnson_, Oct 27 2008