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A028300
a(1) = 1; thereafter a(n+1) = a(n)^2 + n.
7
1, 2, 6, 39, 1525, 2325630, 5408554896906, 29252466072845872288372843, 855706771342998810018458679815602502067088579902657
OFFSET
1,2
FORMULA
a(n) ~ c^(2^n), where c = 1.2574108318043003098123273077302829405940294\ 604970047023808427877694426442... . - Vaclav Kotesovec, Dec 18 2014
EXAMPLE
a(3) = a(2)^2+2 = 4+2 = 6.
MATHEMATICA
RecurrenceTable[{a[1]==1, a[n+1]==a[n]^2 + n}, a, {n, 10}] (* Vaclav Kotesovec, Dec 18 2014 *)
PROG
(Magma) [n le 1 select 1 else Self(n-1)^2 +n-1: n in [1..14]]; // G. C. Greubel, Jan 03 2024
(SageMath)
def a(n): return 1 if n==1 else a(n-1)^2 + n-1 # a = A028300
[a(n) for n in range(1, 15)] # G. C. Greubel, Jan 03 2024
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
A.R. Fink (fink(AT)cadvision.com)
STATUS
approved