A375524 a(n) = denominator of Sum_{i=1..n} 1/A171397(i).

1, 2, 6, 12, 60, 20, 140, 280, 2520, 27720, 27720, 360360, 360360, 360360, 720720, 12252240, 4084080, 77597520, 77597520, 77597520, 1784742960, 1784742960, 8923714800, 8923714800, 80313433200, 11473347600, 332727080400, 332727080400, 10314539492400, 937685408400, 937685408400

Offset: 1

Author

N. J. A. Sloane, Aug 30 2024

Keywords

• nonn
• frac

Examples

			The first few sums are 1, 3/2, 11/6, 25/12, 137/60, 49/20, 363/140, 761/280, 7129/2520, 80939/27720, 83249/27720, 1109957/360360, 1135697/360360, 1159721/360360, 2364487/720720,  ...
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 1..2082

Crossrefs

Cf. A171397, A375805, A375523, A001008/A002805.

Programs

Maple

b:= n-> (l-> add(l[i]*11^(i-1), i=1..nops(l)))(convert(n,base,10)):
g:= proc(n) option remember; `if`(n<1, 0, g(n-1)+1/b(n)) end:
a:= n-> denom(g(n)):
seq(a(n), n=1..31);  # Alois P. Heinz, Aug 30 2024