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 A341899 #10 Jun 04 2021 23:52:28 %S A341899 11,19,17,13,13,23,17,17,31,13,23,41,127,61,23,13,13,67,53,89,19,227, %T A341899 17,29,61,151,31,37,107,53,1741,263,167,23,31,89,61,13,43,241,53,347, %U A341899 1319,19,79,419,521,19,809,677,97,97,1223,89,13,79,67,257,17,499 %N A341899 a(n) is the smallest prime p > 10 such that when strings of n zeros are inserted between every pair of adjacent digits the result is also a prime. %C A341899 First differs from A306920 at n = 13. %C A341899 a(n) = A306920(n) if A306920(n) is < 100, i.e., is a two-digit number. %e A341899 For n = 13: Inserting 13 zeros between all adjacent digits of 127 gives 10000000000000200000000000007, which is prime. Since 127 is the smallest prime where inserting exactly 13 zeros between all adjacent digits results in a number that is also prime, a(13) = 127. %o A341899 (PARI) eva(n) = subst(Pol(n), x, 10) %o A341899 insert_zeros(num, len) = my(d=digits(num), v=[]); for(k=1, #d-1, v=concat(v, concat([d[k]], vector(len)))); v=concat(v, d[#d]); eva(v) %o A341899 a(n) = forprime(p=10, , if(ispseudoprime(insert_zeros(p, n)), return(p))) %Y A341899 Cf. A306920, A344637, A344936, A344937. %K A341899 nonn,base %O A341899 1,1 %A A341899 _Felix Fröhlich_, Jun 04 2021