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 A069619 a(1) = 7; a(2n) = smallest prime that is a right concatenation of a(2n-1) and a number with no insignificant zeros and a(2n+1) = smallest prime ending in ( the least significant digits) a(2n-1). Alternate left and right concatenation yielding primes. 2

%I

%S 7,71,271,2711,52711,5271121,135271121,1352711219,271352711219,

%T 27135271121911,1227135271121911,122713527112191161,

%U 20122713527112191161,20122713527112191161109,2720122713527112191161109

%N a(1) = 7; a(2n) = smallest prime that is a right concatenation of a(2n-1) and a number with no insignificant zeros and a(2n+1) = smallest prime ending in ( the least significant digits) a(2n-1). Alternate left and right concatenation yielding primes.

%e a(4) = 2711 staring with a(3) =271 and a(5) = 52711 in a(4) = 2711.

%Y Cf. A053582, A069605, A069606, A069607, A069608, A069609, A069610, A069611, A069613, A069614, A069615, A069616, A069617, A069618.

%K nonn,base

%O 1,1

%A Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 27 2002

%E More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 30 2003

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