A025531 a(n) = (2nd elementary symmetric function of {1/1, 1/2, ..., 1/n})*(lcm(S))^2, where S = {1,2,...,n}.

2, 36, 210, 6750, 8120, 459620, 2067170, 20522250, 22318758, 2905171038, 3098543448, 554652370272, 584150230092, 612299943684, 2556925522866, 768804781750434, 797490150102074, 297862797402850394, 307475819473818710, 316760108055672710, 325739683035302510, 176916612931176848990

Offset

2,1

Links

Robert Israel, Table of n, a(n) for n = 2..1150

Maple

g:= gfun:-rectoproc({(-n^2-4*n-4)*s(n+1)+(3*n^2+15*n+19)*s(n+2)+(-3*n^2-18*n-27)*s(n+3)+(n^2+7*n+12)*s(n+4), s(0) = 0, s(1) = 0, s(2) = 1/2, s(3) = 1}, s(n), remember):
f:= n -> g(n)*ilcm($1..n)^2:
map(f, [$2..100]); # Robert Israel, Aug 10 2018

Mathematica

nmax = 100;
T = RecurrenceTable[{(-n^2 - 4*n - 4)*s[n+1] + (3*n^2 + 15*n + 19)*s[n+2] + (-3*n^2 - 18*n - 27)*s[n+3] + (n^2 + 7*n + 12)*s[n+4] == 0, s[0] == 0, s[1] == 0, s[2] == 1/2}, s, {n, 0, nmax}];
f[n_] := T[[n+1]]*(LCM @@ Range[n])^2;
Map[f, Range[2, nmax]] (* Jean-François Alcover, Sep 19 2022, after Robert Israel *)

Crossrefs

Sequence in context: A141217 A206688 A226419 * A099903 A341535 A074426

Adjacent sequences: A025528 A025529 A025530 * A025532 A025533 A025534

Keyword

nonn

Author

Clark Kimberling

Extensions

Offset corrected and more terms from Robert Israel, Aug 10 2018

Status

approved