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%I #16 Jul 03 2017 02:13:43
%S 1,1,1,4,2,8,12,30,70,664,1072,8768,11648,37108,95772,1059816,2047488,
%T 12111712,22802028,120779959,337801784,4361743860,11425028900,
%U 142573286216,429917269469,4138239848098,16171519847028,214845911686065
%N Number of ways to arrange integers 1 through n so that the sum of each adjacent pair is prime, not counting reversals.
%C Similar to A036440, but not requiring 1 to be first and n to be last.
%F For n>1, a(n) = A103839(n)/2.
%e a(5)=2 since 1,4,3,2,5 and 3,4,1,2,5 have the property that the sum of each adjacent pair is prime.
%Y Cf. A036440, A051237.
%K nonn,nice
%O 1,4
%A _Jud McCranie_
%E More terms from _Max Alekseyev_, Jan 04 2008
%E a(25)-a(28) from _Giovanni Resta_, Apr 01 2014
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