A282286 - OEIS

%I #8 Feb 11 2017 16:03:27

%S 1,24,195,220,783,612,1763,1200,3135,1984,4899,2964,7055,4140,9603,

%T 5512,12543,7080,15875,8844,19599,10804,23715,12960,28223,15312,33123,

%U 17860,38415,20604,44099,23544,50175,26680,56643,30012,63503,33540,70755,37264,78399

%N Least common multiple of 7*n+1 and 7*n-1.

%H Colin Barker, <a href="/A282286/b282286.txt">Table of n, a(n) for n = 0..1000</a>

%H <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (0,3,0,-3,0,1).

%F a(n) = 49*n^2-1 for n>0 and even.

%F a(n) = (49*n^2-1)/2 for n odd.

%F a(n) = 3*a(n-2) - 3*a(n-4) + a(n-6) for n>6.

%F G.f.: (1+24*x+192*x^2+148*x^3+201*x^4+24*x^5-2*x^6) / ((1-x)^3*(1+x)^3).

%o (PARI) vector(60, n, n--; lcm(7*n+1, 7*n-1))

%o (PARI) Vec((1+24*x+192*x^2+148*x^3+201*x^4+24*x^5-2*x^6) / ((1-x)^3*(1+x)^3) + O(x^60))

%Y Cf. A000466, A136017, A141759, A282284, A282285.

%K nonn,easy

%O 0,2

%A _Colin Barker_, Feb 11 2017