A096529 -id:A096529 - cp's OEIS frontend

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

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, 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, 286, 0, 0, 96, 0, 24, 0, 0, 30, 0, 0, 0, 0, 0, 0, 32, 16, 4, 0, 0

Offset: 1

Reinhard Zumkeller, Jun 23 2004

nonn

a(A096530(n)) = 0, a(A096529(n)) > 0.

For square of terms of A053182(n), a(n) = 6. - Michel Marcus, May 08 2014

			Divisors of n=10 are {1,2,5,10}:
[1,2,10,5]->(1+2+10,2+5+10)=(13,17), [1,10,2,5]->(1+10+2,10+2+5)=(13,17)
[5,2,10,1]->(5+2+10,2+10+1)=(17,13) and
[5,10,2,1]->(5+10+2,10+2+1)=(17,13): therefore a(10)=4.

Cf. A096528, A000005.

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);}
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

More terms from Michel Marcus, May 03 2014

A096530 Numbers whose divisors cannot be permuted so that all sums of triple adjacent divisors are primes.

Original entry on oeis.org

1, 2, 3, 5, 6, 7, 11, 13, 17, 18, 19, 22, 23, 29, 30, 31, 32, 37, 41, 42, 43, 46, 47, 48, 49, 50, 51, 53, 54, 59, 61, 62, 64, 66, 67, 69, 70, 71, 72, 73, 74, 78, 79, 80, 82, 83, 87, 89, 90, 91, 94, 95, 96, 97, 98, 101, 102, 103, 106, 107, 108, 109, 110, 112

Offset: 1

Reinhard Zumkeller, Jun 23 2004

nonn

Amiram Eldar, Table of n, a(n) for n = 1..104

Complement of A096529.

Cf. A096527.

A096527(a(n)) = 0.

48 inserted and more terms added by Michel Marcus, May 03 2014

cp's OEIS Frontend

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

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