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A073676 Rearrangement of odd numbers not divisible by 5 such that every right concatenation of terms is a prime. 1

%I #7 Dec 05 2013 19:55:31

%S 3,1,7,21,23,19,33,9,39,27,59,43,51,47,117,61,287,97,129,83,49,17,171,

%T 157,107,91,29,109,191,397,221,103,63,99,123,321,149,207,393,699,133,

%U 539,93,387,309,273,79,1121,249,457,243,213,137,643,443,693,67,1023,381,623,939,169,663,89,153,679,227,1027

%N Rearrangement of odd numbers not divisible by 5 such that every right concatenation of terms is a prime.

%C The number 11 finally appears as a(201).

%e 3,31,3119,311951,31195117 are all prime.

%t used={3}; num=3; Do[n=1; d=IntegerDigits[num]; While[MemberQ[used,n] || !PrimeQ[newNum=FromDigits[Join[d,IntegerDigits[n]]]], n=n+2]; AppendTo[used,n]; num=newNum, {50}]; used

%K base,nonn

%O 1,1

%A _Amarnath Murthy_, Aug 11 2002

%E Corrected and extended by _T. D. Noe_, Jan 25 2011

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Last modified April 18 03:33 EDT 2024. Contains 371767 sequences. (Running on oeis4.)