A278248 Least number with the same prime signature as the n-th number in Perrin sequence: a(n) = A046523(A001608(n)), a(1) = 0.

2, 0, 2, 2, 2, 2, 2, 2, 6, 12, 2, 6, 2, 6, 6, 12, 60, 6, 6, 6, 2, 2, 96, 60, 2, 30, 6, 6, 6, 840, 30, 6, 30, 6, 2, 6, 6, 60, 2, 420, 1260, 30, 30, 420, 210, 30, 30, 210, 6, 30, 30, 12, 6, 2310, 30, 840, 6, 240, 6, 30, 6, 420, 6, 6, 30, 420, 6, 210, 6, 6, 6, 4620, 60, 210, 30030, 2, 6, 30, 2310, 13860, 60, 210, 6, 6, 6, 120, 6, 2310, 210, 210, 6, 210, 30, 60, 4620

Offset: 0

Author

Antti Karttunen, Nov 16 2016

Keywords

• nonn

Comments

This sequence works as a "sentinel" for Perrin sequence by matching to any other sequence that is obtained as f(A001608(n)), where f(n) is any function that depends only on the prime signature of n (see the index entry for "sequences computed from exponents in ..."). As of Nov 11 2016 no such sequences were present in the database.

Links

• Antti Karttunen, Table of n, a(n) for n = 0..555
• Index entries for sequences computed from exponents in factorization of n

Crossrefs

Cf. A001608, A046523, A278241, A278245.

Programs

PARI

A046523(n) = my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]) \\ From Charles R Greathouse IV, Aug 17 2011
p0 = 3; p1 = 0; p2 = 2; for(n=0, 555, write("b278248.txt", n, " ", if(!p0,p0,A046523(p0))); old_p0 = p0; old_p1 = p1; p0 = p1; p1 = p2; p2 = old_p1 + old_p0; );

Scheme

(define (A278248 n) (if (= 1 n) 0 (A046523 (A001608 n))))

Formula

a(1) = 0; for any other n, a(n) = A046523(A001608(n)).