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A068650 Primes in which a string of 1's is sandwiched between two 3's. 1
313, 3111111111113, 311111111111113, 3111111111111111111111111111113, 311111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111113 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

MAPLE

a := 3:b := 1:i := 1:for n from 0 to 500 do c := a+10*(10^n-1)/9*b+10^(n+1)*a; if(isprime(c)) then d[i] := c; i := i+1; end if; end do:q := seq(d[j], j=1..i-1);

CROSSREFS

Cf. A068645, A068646, A068647, A068648, A068649.

Sequence in context: A123059 A083997 A164772 * A106156 A107116 A107115

Adjacent sequences:  A068647 A068648 A068649 * A068651 A068652 A068653

KEYWORD

base,nonn

AUTHOR

Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Feb 28 2002

EXTENSIONS

More terms from Sascha Kurz (sascha.kurz(AT)uni-bayreuth.de), Mar 19 2002

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Last modified February 16 08:13 EST 2012. Contains 205893 sequences.