A060824 4-wave sequence beginning with 2s.

2, 2, 2, 2, 4, 6, 8, 14, 18, 20, 38, 52, 60, 112, 150, 170, 320, 432, 492, 924, 1244, 1414, 2658, 3582, 4074, 7656, 10314, 11728, 22042, 29698, 33772, 63470, 85512, 97240, 182752, 246222, 279994, 526216, 708968, 806208, 1515176, 2041392, 2321386

Offset

2,1

Comments

Primes are the numbers >=2 which have no nontrivial divisor: a(p)=0.

Also: a(n)= A032741(n)-1, n>=2 (from number of divisors <n, called proper divisors).

Links

Table of n, a(n) for n=2..44.

F. v. Lamoen, Wave sequences

Index entries for linear recurrences with constant coefficients, signature (1, -1, 3, -3, 3, 0, 0, 0, -1, 1, -1).

Formula

a(n) = 2*A038197(n-2).

a(n)=2*a(n-3)+3*a(n-6)-a(n-9)-a(n-12) - Antonio G. Astudillo (afg_astudillo(AT)hotmail.com), Jan 12 2003

G.f.: -2*x^2*(x^5-2*x^4+2*x^3-x^2-1)/((x^2-x+1)*(x^9-3*x^3+1)). - Colin Barker, Nov 09 2012

Crossrefs

Cf. A038197.

Sequence in context: A126663 A032600 A103260 * A334125 A364811 A244459

Adjacent sequences: A060821 A060822 A060823 * A060825 A060826 A060827

Keyword

easy,nonn

Author

Jason Earls, May 01 2001

Status

approved