OFFSET
1,1
LINKS
Colin Barker, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,0,0,0,0,-1).
FORMULA
a(n) = 2*a(n-12) - a(n-24). - R. J. Mathar, Feb 12 2019
G.f.: x*(12 + 6*x + 4*x^2 + 3*x^3 + 60*x^4 + 2*x^5 + 84*x^6 + 6*x^7 + 12*x^8 + 30*x^9 + 132*x^10 + x^11 + 132*x^12 + 30*x^13 + 12*x^14 + 6*x^15 + 84*x^16 + 2*x^17 + 60*x^18 + 3*x^19 + 4*x^20 + 6*x^21 + 12*x^22) / (x^24 - 2*x^12 + 1). - Colin Barker, Mar 05 2019
Sum_{k=1..n} a(k) ~ (703/288)*n^2. - Amiram Eldar, Oct 07 2023
PROG
(PARI) for(n=1, 100, print1(lcm(12, n)/gcd(n, 12), ", "))
(PARI) Vec(x*(12 + 6*x + 4*x^2 + 3*x^3 + 60*x^4 + 2*x^5 + 84*x^6 + 6*x^7 + 12*x^8 + 30*x^9 + 132*x^10 + x^11 + 132*x^12 + 30*x^13 + 12*x^14 + 6*x^15 + 84*x^16 + 2*x^17 + 60*x^18 + 3*x^19 + 4*x^20 + 6*x^21 + 12*x^22) / (x^24 - 2*x^12 + 1) + O(x^60)) \\ Colin Barker, Mar 05 2019
(Python)
from math import gcd, lcm
def a(n): return lcm(12, n)//gcd(12, n)
print([a(n) for n in range(1, 65)]) # Michael S. Branicky, Dec 06 2021
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Amarnath Murthy, May 10 2002
EXTENSIONS
More terms from Benoit Cloitre, May 16 2002
STATUS
approved