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.
%I A131581 #11 Aug 15 2017 17:14:28
%S A131581 2,5,11,37,101,317,1009,3163,10007,31627,100003,316241,1000003,
%T A131581 3162283,10000019,31622777,100000007,316227767,1000000007,3162277669,
%U A131581 10000000019,31622776621,100000000003,316227766069,1000000000039
%N A131581 The next prime greater than the square root of 10^n.
%C A131581 The difference between a(n) and floor(sqrt(10^n)): 1, 2, 1, 6, 1, 1, 9, 1, 7, 5, 3, 14, 3, 6, 19, 1, 7, 1, 7, 9, ....
%C A131581 Values for which the difference between a(n) and floor(sqrt(10^n)) equals one: 0, 2, 4, 5, 7, 15, 17, 25, 145, 1079, ..., (1350). Only even terms are 0, 2 & 4; all the rest must be odd.
%F A131581 a(n) = sqrt(A175733(n+1)). [From _Jaroslav Krizek_, Aug 24 2010]
%t A131581 NextPrim[n_] := Block[{k = n + 1}, While[ !PrimeQ[k], k++ ]; k]; Table[ NextPrim@ Floor@ Sqrt[10^n], {n, 0, 25}]
%t A131581 Table[NextPrime[Sqrt[10^n]],{n,0,30}] (* _Harvey P. Dale_, Aug 15 2017 *)
%Y A131581 Cf. A003617, A132153, A136582, A175733, A175734.
%K A131581 easy,nonn
%O A131581 0,1
%A A131581 _Robert G. Wilson v_, Jan 12 2007