A260231 a(n) = Product_{k=1..n} (1 + k^k).

2, 10, 280, 71960, 224946960, 10495350312720, 8643382777938679680, 145011908479540041684850560, 56180584638978557924165229531974400, 561805846445966163880630853243909229531974400, 160289764609087349005207761687490741791453382934816332800

Offset: 1

Author

Vaclav Kotesovec, Jul 20 2015

Keywords

• nonn

Crossrefs

Cf. A000312, A002109, A028361, A054640, A082480, A217757, A258325.

Programs

Mathematica

Table[Product[1+k^k,{k,1,n}],{n,1,12}]
FoldList[Times,Table[1+k^k,{k,12}]] (* Harvey P. Dale, Jul 19 2025 *)

Formula

a(n) ~ c * A002109(n), where c = Product_{k>=1} (1 + 1/k^k) = 2.60361190459951423330221282635022049352582879064202503882732200701325334...