This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
a8(n) = my(k=1); while(!isprime(k*n*2^n+1), k+=2); k; a9(n) = my(k=1); while(!isprime(k*n*2^n-1), k+=2); k; isok(n) = a8(n) == a9(n); \\ Michel Marcus, Sep 15 2019
1*1*2^1+1=3 prime so a(1)=1. 1*2*2^2+1=9 composite, 3*2*2^2+1=25 composite, 5*2*2^2+1=41 prime so a(2)=5. 1*3*2^3+1=25 composite, 3*3*2^3=73 prime so a(3)=3.
Q:= proc(m) local k; for k from 1 by 2 do if isprime(k*m+1) then return k fi od end proc: seq(Q(n*2^n), n=1..100); # Robert Israel, Jan 05 2016
Table[k = 1; While[!PrimeQ[k*n*2^n + 1], k += 2]; k, {n, 73}] (* Michael De Vlieger, Apr 21 2015 *)
a(n) = k=1; while(!isprime(k*n*2^n+1), k+=2); k \\ Colin Barker, Apr 21 2015
ABC2 $b*$a*2^$a+1 // {number_primes,$b,1}
a: from 1 to 10000
b: from 1 to 100000 step 2
Charles R Greathouse IV, Apr 24 2015
The first few rows are n=2: 1 n=3: 2, 0 n=4: 1, 0 n=5: 2, 0, 0, 3 n=6: 1, 0
T:= proc(n,k) local x;
if igcd(n,k) <> 1 then return NULL fi;
for x from 0 do if isprime(x*n+k) then return x fi
od
end proc:
seq(seq(T(n,k),k=1..n-1),n=2..30);
Table[Map[Catch@ Do[x = 0; While[! PrimeQ[x n + #], x++]; Throw@ x, {10^3}] &, Range@ n /. k_ /; GCD[k, n] > 1 -> Nothing], {n, 2, 19}] // Flatten (* Michael De Vlieger, Jan 06 2016 *)
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