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A108830 Primes such that the outer 2 digits are n and n-1 and all inner digits are 2, where 0 < n < 9. 0
827, 2221, 42223, 4222222223, 42222222223, 222222222222222221, 822222222222222222227, 42222222222222222222222222222223, 8222222222222222222222222222222227, 822222222222222222222222222222222222222222222222222222222222227 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..10.

MATHEMATICA

Sort[Select[Flatten[Table[FromDigits[Join[{n}, PadRight[{}, i, 2], {n-1}]], {n, 2, 8, 2}, {i, 70}]], PrimeQ]] (* Harvey P. Dale, Dec 05 2015 *)

PROG

(PARI) n10np1(n, d) = { local(x, y, k); for(x=1, n, for(k=1, 8, y=10^(x+1)*k+floor(10^x*d/9)*10+k-1; if(isprime(y), print1(y", ")) ) ) }

CROSSREFS

Sequence in context: A143799 A046496 A102350 * A134726 A104281 A217551

Adjacent sequences:  A108827 A108828 A108829 * A108831 A108832 A108833

KEYWORD

easy,nonn,base

AUTHOR

Cino Hilliard, Jul 11 2005

EXTENSIONS

One more term (a(10)) from Harvey P. Dale, Dec 05 2015

STATUS

approved

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Last modified September 21 13:20 EDT 2020. Contains 337272 sequences. (Running on oeis4.)