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A227365 a(n) = 0 + 1*2 + 3*4*5 + 6*7*8*9 + ... + ...*n. 5

%I

%S 0,1,2,5,14,62,68,104,398,3086,3096,3196,4406,20246,243326,243341,

%T 243566,247406,316766,1638686,28150526,28150547,28150988,28161152,

%U 28405550,34526126,193916126,4503821726,4503821754,4503822538,4503846086,4504576886,4527986846,5301270686

%N a(n) = 0 + 1*2 + 3*4*5 + 6*7*8*9 + ... + ...*n.

%H Seiichi Manyama, <a href="/A227365/b227365.txt">Table of n, a(n) for n = 0..10000</a>

%e a(4) = 0 + 1*2 + 3*4 = 14.

%e a(5) = 0 + 1*2 + 3*4*5 = 62.

%e a(6) = 0 + 1*2 + 3*4*5 + 6 = 68.

%o (Python)

%o for n in range(55):

%o sum = i = 0

%o k = 1

%o while i<=n:

%o product = 1

%o for x in range(k):

%o product *= i

%o i += 1

%o if i>n: break

%o sum += product

%o k += 1

%o print(str(sum), end=',')

%Y Cf. A227363, A227364, A227366, A227367.

%K nonn

%O 0,3

%A _Alex Ratushnyak_, Jul 07 2013

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Last modified September 20 03:47 EDT 2021. Contains 347577 sequences. (Running on oeis4.)