A189046 a(n) = lcm(n,n+1,n+2,n+3,n+4,n+5)/60.
0, 1, 7, 14, 42, 42, 462, 462, 858, 3003, 1001, 4004, 6188, 18564, 27132, 3876, 27132, 74613, 100947, 67298, 17710, 230230, 296010, 188370, 237510, 118755, 736281, 453096, 553784, 1344904, 324632
Offset: 0
Links
- Nathaniel Johnston, Table of n, a(n) for n = 0..2000
- Index entries for linear recurrences with constant coefficients, signature (0, 0, 0, 0, 7, 0, 0, 0, 0, -28, 0, 0, 0, 0, 84, 0, 0, 0, 0, -203, 0, 0, 0, 0, 413, 0, 0, 0, 0, -728, 0, 0, 0, 0, 1128, 0, 0, 0, 0, -1554, 0, 0, 0, 0, 1918, 0, 0, 0, 0, -2128, 0, 0, 0, 0, 2128, 0, 0, 0, 0, -1918, 0, 0, 0, 0, 1554, 0, 0, 0, 0, -1128, 0, 0, 0, 0, 728, 0, 0, 0, 0, -413, 0, 0, 0, 0, 203, 0, 0, 0, 0, -84, 0, 0, 0, 0, 28, 0, 0, 0, 0, -7, 0, 0, 0, 0, 1).
- Index entries for sequences related to lcm's.
Programs
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Maple
seq(lcm(n,n+1,n+2,n+3,n+4,n+5)/60,n=0..30)
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Mathematica
Table[(LCM@@(n+Range[0,5]))/60,{n,0,40}] (* Harvey P. Dale, Apr 17 2011 *) -
PARI
a(n)=lcm([n..n+5])/60 \\ Charles R Greathouse IV, Sep 30 2016
Formula
a(n) = n*(n+1)*(n+2)*(n+3)*(n+4)*(n+5)*(4*(n^4 mod 5)+1)/(1800*((n^3 mod 4)+((n-1)^3 mod 4)+1)).
a(n) = binomial(n+5,6)/(gcd(n,5)*(A021913(n-1)+1)).
a(n) = binomial(n+5,6)/(gcd(n,5)*floor(((n-1) mod 4)/2+1)). - Gary Detlefs, Apr 22 2011
Sum_{n>=1} 1/a(n) = 92 + (54/5-18*sqrt(5)+6*sqrt(178-398/sqrt(5)))*Pi. - Amiram Eldar, Sep 29 2022
Comments