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A175565 a(n) = smallest prime > a(n-1) such that in the sum a(n-1) + a(n) there are no carries, with a(1)=2. 0

%I

%S 2,3,5,11,13,23,31,37,41,43,53,101,103,113,131,137,151,211,223,233,

%T 241,251,307,311,313,331,337,401,421,431,433,443,503,1009

%N a(n) = smallest prime > a(n-1) such that in the sum a(n-1) + a(n) there are no carries, with a(1)=2.

%C For each digit place we must have sum of digits of a(n) and a(n-1) less than 10.

%C The sequence terminates if a(n) is a prime of form 10k+9 (A030433).

%C It seems very likely that the sequence is finite for any a(1).

%C E.g., sequence with a(1)=1013 terminates at a(8060)=10000019.

%e After 5 we cannot use 7 because 5 + 7 = 12 and here 1 carries to the next digit place.

%K fini,full,nonn,base

%O 1,1

%A _Zak Seidov_, Jul 11 2010

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Last modified December 7 20:33 EST 2019. Contains 329849 sequences. (Running on oeis4.)