OFFSET
1,1
COMMENTS
It is assumed that a pair of twin primes is characterized by its mean. The median of an even number of values is taken as the arithmetic mean of the two central elements in their sorted list.
EXAMPLE
a(1): 2 pairs {3,5}, {5,7}, median = mean of {4,6} = 5;
a(2): 6 pairs {11,13}, {17,19}, {29,31}, {41,43}, {59,61}, {71,73}, median = mean of {30,42} = 36.
MATHEMATICA
a[n_]:=Module[{s={}, p=NextPrime[10^(n-1)]}, While[p<10^n-4, If[PrimeQ[p+2], AppendTo[s, p+1]]; p=NextPrime[p]]; Median[s]]; Array[a, 7] (* James C. McMahon, Sep 02 2025 *)
CROSSREFS
KEYWORD
nonn,base,more
AUTHOR
Hugo Pfoertner, Sep 02 2025
STATUS
approved
