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a(n) is smallest prime > 10*a(n-1), a(1) = 3.
1

%I #11 Jun 18 2018 03:26:31

%S 3,31,311,3119,31193,311951,3119533,31195343,311953441,3119534441,

%T 31195344413,311953444133,3119534441393,31195344413953,

%U 311953444139539,3119534441395579,31195344413955853,311953444139558593

%N a(n) is smallest prime > 10*a(n-1), a(1) = 3.

%H Harry J. Smith, <a href="/A065533/b065533.txt">Table of n, a(n) for n = 1..100</a>

%t NextPrim[n_Integer] := Block[ {k = n + 1}, While[ !PrimeQ[k], k++ ]; Return[k]]; a[1] = 3; a[n_] := NextPrim[ 10*a[n - 1]]; Table[ a[n], {n, 1, 20} ]

%t NestList[NextPrime[10#]&,3,20] (* _Harvey P. Dale_, Jul 04 2012 *)

%o (PARI) { for (n=1, 100, if (n>1, a=nextprime(10*a), a=3); write("b065533.txt", n, " ", a) ) } \\ _Harry J. Smith_, Oct 21 2009

%Y Cf. A065122.

%K nonn

%O 1,1

%A _Robert G. Wilson v_, Nov 28 2001