**a(1)=1; for n > 1, a(n) is the smallest number that is formed by arranging the decimal numbers "1", "2", ..., "n" in some order so that the sum of every pair of adjacent numbers "i" "j" is prime.**

*1, 12, 123, 1234, 14325, 143256, 1234765, 12347658, 123476589, 1012347658*

*7 seqfan posts*

*Wed Mar 16 19:00:00 CET 2011* [seqfan] Re: A187871

*Wed Mar 16 18:01:42 CET 2011* [seqfan] Re: A187871

*Tue Mar 15 18:12:57 CET 2011* [seqfan] Re: A187871

*Tue Mar 15 17:32:43 CET 2011* [seqfan] Re: put the numbers from 1 to n such the sum of two of them are prime

*Tue Mar 15 01:58:29 CET 2011* [seqfan] Re: put the numbers from 1 to n such the sum of two of them are prime

*Mon Mar 14 17:08:23 CET 2011* [seqfan] Re: put the numbers from 1 to n such the sum of two of them are prime

*Mon Mar 14 16:28:56 CET 2011* [seqfan] Re: put the numbers from 1 to n such the sum of two of them are prime

Index of A-numbers in seqfan: by ascending order
by month
by frequency
by keyword

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