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A282285
Least common multiple of 5*n+1 and 5*n-1.
3
1, 12, 99, 112, 399, 312, 899, 612, 1599, 1012, 2499, 1512, 3599, 2112, 4899, 2812, 6399, 3612, 8099, 4512, 9999, 5512, 12099, 6612, 14399, 7812, 16899, 9112, 19599, 10512, 22499, 12012, 25599, 13612, 28899, 15312, 32399, 17112, 36099, 19012, 39999, 21012
OFFSET
0,2
FORMULA
a(n) = 25*n^2-1 for n>0 and even.
a(n) = (25*n^2-1)/2 for n odd.
a(n) = 3*a(n-2) - 3*a(n-4) + a(n-6) for n>6.
G.f.: (1+12*x+96*x^2+76*x^3+105*x^4+12*x^5-2*x^6) / ((1-x)^3*(1+x)^3).
PROG
(PARI) vector(60, n, n--; lcm(5*n+1, 5*n-1))
(PARI) Vec((1+12*x+96*x^2+76*x^3+105*x^4+12*x^5-2*x^6) / ((1-x)^3*(1+x)^3) + O(x^60))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Colin Barker, Feb 11 2017
STATUS
approved