0,4

In calculating this sequence, some backtracking may be needed to ensure that the sequence is unbounded. For instance, one makes the preliminary assignment a(4) = 6, since determinant[1,1,3,6] = 3, a prime greater than the previous determinant prime in A119839: 2. Then one computes a(5) = 23, giving determinant[1,3,6,23] = 5. However, the sequence hits a wall here, as any putative a(6) gives a composite determinant divisible by 3, hence we must backtrack and reassign a(4) = 8. The associated sequence of primes A119839 = 2, 5, 7, 13, 23, 149, 277, 331, 9433, ...

a(0) = a(1) = a(2) = 1; for n>2: a(n) = min{k such that k*a(n-3) - a(n-1)*a(n-2) is prime p, p>A119839(n-1)}. determinant [a(n-3),a(n-2),a(n-1),a(n)] = a(n)*a(n-3) - a(n-1)*a(n-2) is a prime greater than any previous prime in the associated sequence of primes A119839.

a(6) = 87 because the of the prime determinant 13 =

|.3..8|

|31.87|.

Cf. A000040, A119839.

Sequence in context: A078619 A066304 A066165 this_sequence A108492 A003470 A022563

Adjacent sequences: A119835 A119836 A119837 this_sequence A119839 A119840 A119841

easy,nonn

Jonathan Vos Post (jvospost2(AT)yahoo.com), May 25 2006