A048552 a(n+1) is next smallest prime beginning with a(n), initial prime is a(0) = 7.

7, 71, 719, 7193, 71933, 719333, 71933317, 719333177, 71933317711, 7193331771103, 71933317711039, 7193331771103939, 719333177110393913, 7193331771103939133, 719333177110393913323, 71933317711039391332309, 719333177110393913323097, 719333177110393913323097047

Offset: 0

Author

Patrick De Geest, May 15 1999

Keywords

• nonn
• base

Links

• Robert Israel, Table of n, a(n) for n = 0..250

Crossrefs

Cf. A048549, A048550, A048551, A048552, A048553, A048554, A048555, A048556.

Programs

Maple

f:= proc(n) option remember; local q,d,v;
    q:=procname(n-1);
    for d from 1 do
      v:= nextprime(q*10^d);
      if v < (q+1)*10^d then return v fi
    od
end proc:
f(0):= 7:
map(f, [$0..20]); # Robert Israel, Jan 26 2020

Mathematica

Nest[Function[{a, n}, Append[#, Catch@ Do[Do[If[PrimeQ@ #, Throw@ #; Break[], #] &@ FromDigits[n~Join~PadLeft[IntegerDigits[(5 j - 4 + Mod[3 j + 2, 4])/2], i]], {j, 4*10^(i - 1)}], {i, Infinity}]]] @@ {#, IntegerDigits[#[[-1]] ]} &, {7}, 17] (* Michael De Vlieger, Jan 26 2020 *)

PARI

next_A048552(p)=for(i=1,oo,my(q=nextprime(p*=10));q-p>10^i||return(q))
A048552(n,p=7)=vector(n,i,i>1&&p=next_A048552(p);p) \\ M. F. Hasler, Jan 26 2020