A069612 a(1) = 19 (the smallest prime ending in a 9) and a(n+1) = smallest prime ending in a(n).

19, 419, 5419, 35419, 435419, 11435419, 111435419, 9111435419, 89111435419, 1389111435419, 81389111435419, 381389111435419, 15381389111435419, 3315381389111435419, 153315381389111435419, 22153315381389111435419, 2022153315381389111435419

Offset

1,1

Links

Michael S. Branicky, Table of n, a(n) for n = 1..367 (terms 1..300 from Harvey P. Dale)

Mathematica

w=9; Table[w; i=1; While[PrimeQ[ToExpression[StringJoin[ToString[i], ToString[w]]]]==False, i++ ]; w=ToExpression[StringJoin[ToString[i], ToString[w]]], {32}]
nxt[n_]:=Module[{c=10^IntegerLength[n], x=1}, While[!PrimeQ[c*x+n], x++]; c*x+n]; NestList[nxt, 19, 15] (* Harvey P. Dale, Sep 25 2013 *)

Prog

(Python)
from sympy import isprime
from itertools import count, islice
def agen(an=19):
    while True:
        yield an
        pow10 = 10**len(str(an))
        for t in count(pow10+an, step=pow10):
            if isprime(t):
                an = t
                break
print(list(islice(agen(), 17))) # Michael S. Branicky, Jun 23 2022

Crossrefs

Cf. A053582, A053583, A053584.

Sequence in context: A172816 A202040 A244765 * A077716 A089573 A284332

Adjacent sequences: A069609 A069610 A069611 * A069613 A069614 A069615

Keyword

nonn,base

Author

Amarnath Murthy, Mar 27 2002

Extensions

More terms from Hans Havermann, Jun 06 2002

Status

approved