A069257 Denominator of the last term of the Egyptian fraction sum (using the greedy algorithm) which satisfies 1 = 1/n + 1/(n+1) + 1/(n+2) ... 1/a(n).

6, 20, 57960, 3145940416080, 5765760, 288680192354725622464710969631440008928, 20484953806009937929429725901717124022833778640, 59553628273094395440, 102119994931499628863688098762720537989600

Offset: 2

Author

Christopher Lund (clund(AT)san.rr.com), Apr 14 2002

Keywords

• easy
• frac
• nonn

Comments

The next term in the series, a(11), is 7*10^192.

Examples

			Since 1 = 1/3 + 1/4 + 1/5 + 1/6 + 1/20, a(3) = 20.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 2..14

Programs

Mathematica

a[n_] := Module[{s = 1/n, k = n}, While[s < 1, k = Max[k + 1, Ceiling[1/(1 - s)]]; s += 1/k]; k]; Array[a, 9, 2] (* Amiram Eldar, Oct 18 2019 *)