OFFSET
1,1
FORMULA
a(n) = n*[A079782(n)-(n-1)/2]. - R. J. Mathar, Nov 12 2006
EXAMPLE
The fifth row 55,56,57,58,59 is divisible by 5,4,3,2 and 1 respectively.
MATHEMATICA
a[n_] := n*(Which[n == 1, 2, n == 2, 5, n == 3, 11, True, LCM @@ Range[n] - 1] - (n-1)/2);
Table[a[n], {n, 1, 30}] (* Jean-François Alcover, Jun 17 2024 *)
PROG
(PARI) okrow(m, n) = {v = vector(n, i, i+m-1); for (i=1, n, if (v[i] % (n-i+1), return (0)); ); return (1); }
a(n) = {m = n+1; while (! okrow(m, n), m++); sum(k=1, n, m+k-1); } \\ Michel Marcus, Feb 28 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Amarnath Murthy, Feb 03 2003
EXTENSIONS
More terms from Michel Marcus, Feb 28 2014
STATUS
approved