OFFSET
0,2
COMMENTS
a(1) = 31 is the third Mersenne prime. a(8) = 248 is the dimensions of E_8. a(16) = 496 is the third perfect number. - Pol
a(n)^340 = 155 mod 341 unless a(n) is also divisible by 11. - Alonso del Arte, Feb 15 2012
Number of sides on n triacontakaihenagons (31-gons). - Wesley Ivan Hurt, Oct 25 2016
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
Luis Manuel Rivera, Integer sequences and k-commuting permutations, arXiv preprint arXiv:1406.3081, 2014
Index entries for linear recurrences with constant coefficients, signature (2,-1).
FORMULA
a(n) = 31*n.
From G. C. Greubel, Oct 24 2016: (Start)
G.f.: (31*x)/(1 - x)^2.
E.g.f.: 31*x*exp(x).
a(n) = 2*a(n-1) - a(n-2). (End)
EXAMPLE
a(8) = 31 * 8 = 248. a(16) = 31 * 16 = 496.
MAPLE
with(numtheory):a:=proc(n) if n=0 then 0 else mcombine(7*n, 3*n, 5*n, 11*n) fi end: seq(a(n), n=0..45); # Zerinvary Lajos, Apr 11 2008
MATHEMATICA
Range[0, 3000, 31] (* Vladimir Joseph Stephan Orlovsky, Jun 03 2011 *)
LinearRecurrence[{2, -1}, {0, 31}, 25] (* G. C. Greubel, Oct 24 2016 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Omar E. Pol, Nov 25 2007
STATUS
approved