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A069612 a(1) = 19 (the smallest prime ending in a 9) and a(n+1) = smallest prime ending in a(n). 5
19, 419, 5419, 35419, 435419, 11435419, 111435419, 9111435419, 89111435419, 1389111435419, 81389111435419, 381389111435419, 15381389111435419, 3315381389111435419, 153315381389111435419, 22153315381389111435419, 2022153315381389111435419 (list; graph; refs; listen; history; text; internal format)
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

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Last modified November 30 09:21 EST 2022. Contains 358438 sequences. (Running on oeis4.)