A175565 - OEIS

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.

2, 3, 5, 11, 13, 23, 31, 37, 41, 43, 53, 101, 103, 113, 131, 137, 151, 211, 223, 233, 241, 251, 307, 311, 313, 331, 337, 401, 421, 431, 433, 443, 503, 1009

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OFFSET

1,1

COMMENTS

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

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

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

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

LINKS

Table of n, a(n) for n=1..34.

EXAMPLE

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

CROSSREFS

Sequence in context: A235631 A180640 A128425 * A262831 A036960 A133783

Adjacent sequences: A175562 A175563 A175564 * A175566 A175567 A175568

KEYWORD

fini,full,nonn,base

AUTHOR

Zak Seidov, Jul 11 2010

STATUS

approved