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A096527 Number of permutations of divisors of n such that all sums of triple adjacent divisors are primes.

%I A096527 #14 May 09 2014 06:44:50
%S A096527 0,0,0,6,0,0,0,12,6,4,0,12,0,4,4,4,0,0,0,16,12,0,0,20,6,4,12,20,0,0,0,
%T A096527 0,4,4,24,48,0,4,12,50,0,0,0,4,12,0,0,0,0,0,0,16,0,0,24,136,12,4,0,
%U A096527 286,0,0,96,0,24,0,0,30,0,0,0,0,0,0,32,16,4,0,0
%N A096527 Number of permutations of divisors of n such that all sums of triple adjacent divisors are primes.
%C A096527 a(A096530(n)) = 0, a(A096529(n)) > 0.
%C A096527 For square of terms of A053182(n), a(n) = 6. - _Michel Marcus_, May 08 2014
%e A096527 Divisors of n=10 are {1,2,5,10}:
%e A096527 [1,2,10,5]->(1+2+10,2+5+10)=(13,17), [1,10,2,5]->(1+10+2,10+2+5)=(13,17)
%e A096527 [5,2,10,1]->(5+2+10,2+10+1)=(17,13) and
%e A096527 [5,10,2,1]->(5+10+2,10+2+1)=(17,13): therefore a(10)=4.
%o A096527 (PARI) isokperm(v, nbd, d) = {for (j=1, nbd-2, if (! isprime(d[v[j]] + d[v[j+1]] + d[v[j+2]]), return (0));); return (1);}
%o A096527 a(n) = {d = divisors(n); nbd = #d; if (nbd > 2, sum(i=1, nbd!, isokperm(numtoperm(nbd, i), nbd, d)));} \\ _Michel Marcus_, May 03 2014
%Y A096527 Cf. A096528, A000005.
%K A096527 nonn
%O A096527 1,4
%A A096527 _Reinhard Zumkeller_, Jun 23 2004
%E A096527 More terms from _Michel Marcus_, May 03 2014