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A088061
a(1) = 11, a(n) = smallest prime obtained by starting with a(n-1) and prefixing it with one or more copies of (the decimal expansion of) n.
2
11, 211, 33211, 44433211, 5544433211, 65544433211, 77777777777765544433211
OFFSET
1,1
COMMENTS
Next term has 657 digits and is too large to include. - David Wasserman, Jul 01 2005
a(9) has 1280 digits: 623 repeats of "9" + 634 repeats of "8" + 12 repeats of "7" + "65544433211". a(10) has 4990 digits: 1855 repeats of "10" + a(9). a(8), a(9), a(10) are verified by PARI ispseudoprime function. - Dmitry Petukhov, Oct 15 2017
EXAMPLE
a(3) = 33211 as 3211 is not a prime but 33211 is.
PROG
(PARI) x=0; n=-1; for(k=1, 9, z=n; while(1, n++; x=x+k*10^n; if(ispseudoprime(x), print(x); break))) \\ Dmitry Petukhov, Oct 15 2017
CROSSREFS
Cf. A088062.
Sequence in context: A112704 A243674 A114758 * A070220 A134069 A137464
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Sep 21 2003
STATUS
approved