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A090262 Numbers n such that the strings n1n and 1n1 are both prime. 4


%S 3,9,17,29,47,51,81,87,113,117,131,141,201,239,291,333,359,371,393,

%T 443,459,489,509,539,573,623,663,681,749,819,821,873,903,947,1071,

%U 1077,1161,1269,1533,1563,1589,1613,1637,1673,1767,1773,1821,1841,1883,1959,1977

%N Numbers n such that the strings n1n and 1n1 are both prime.

%H Daniel Starodubtsev, <a href="/A090262/b090262.txt">Table of n, a(n) for n = 1..10000</a>

%e 9 is a member as 919 and 191 are both prime.

%Y Cf. A090263, A090264, A090265.

%K base,nonn

%O 1,1

%A _Amarnath Murthy_, Nov 28 2003

%E More terms from mohammed bouayoun (bouyao(AT)wanadoo.fr), Feb 02 2004

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Last modified December 4 09:35 EST 2020. Contains 338923 sequences. (Running on oeis4.)