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%I #11 Jan 21 2019 19:01:55
%S 2,4,8,18,30,68,128,258,508,1030,2052,4092,8192,16400,32792,65520,
%T 131058,262172,524286,1048596,2097156,4194312,8388620,16777210,
%U 33554472,67108860,134217738,268435446,536870858,1073741832,2147483616
%N (Smallest prime >= 2^n) + (largest prime <= 2^n).
%C For n=0 we just take a(0)=2, the least prime >= 2^0, as there is no prime <= 2^0. - _Robert Israel_, Nov 01 2018
%H Robert Israel, <a href="/A092507/b092507.txt">Table of n, a(n) for n = 0..3317</a>
%F a(n) = A014210(n) + A014234(n) for n >= 2. - _Robert Israel_, Nov 01 2018
%p [2, seq( (nextprime(2^x-1)+prevprime(2^x+1)),x=1..20)]; # Corrected by _Robert Israel_, Nov 01 2018
%t PrevPrim[n_] := Block[{k = n - 1}, While[ !PrimeQ[k], k-- ]; k]; NextPrim[n_] := Block[{k = n + 1}, While[ !PrimeQ[k], k++ ]; k]; Table[PrevPrim[2^n+1] + NextPrim[2^n-1], {n, 31}] (* _Robert G. Wilson v_, Apr 14 2004 *)
%Y Cf. A014210, A014234, A058249.
%K nonn
%O 0,1
%A _Jorge Coveiro_, Apr 05 2004
%E More terms from _Robert G. Wilson v_, Apr 14 2004
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