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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