OFFSET
0,2
COMMENTS
After 2, can this ever be prime? This is to A001923 Sum k^k, k=1..n, as k^k^k is to k^k.
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..26
FORMULA
a(n) = Sum_{i=0..n} i^(i^2). a(n) = Sum_{i=0..n} (i^i)^i. In this sequence, we formally define 0^0 = 1.
EXAMPLE
a(0) = 1 because A002489(0) is given formally as 0^0^0 = 1.
a(1) = 2 because 1 + (1^1)^1 = 1 + 1 = 2.
a(2) = 18 because 2 + (2^2)^2 = 2 + 16 = 18.
a(3) = 19701 because 18 + (3^3)^3 = 18 + 19683 = 19701.
a(4) = 4294986997 = 19701 + (4^4)^4 = 19701 + 4294967296.
MATHEMATICA
Accumulate[Join[{1}, Table[n^(n^2), {n, 9}]]] (* Harvey P. Dale, Apr 10 2014 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Aug 18 2006
EXTENSIONS
More terms from Harvey P. Dale, Apr 10 2014
STATUS
approved