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A227367 a(0)=1, a(n+1) = a(0) + a(1)*a(2) + a(3)*a(4)*a(5) + a(6)*a(7)*a(8)*a(9) + ... + ...*a(n). 5
1, 1, 2, 3, 6, 21, 381, 762, 290703, 84397476747, 7122934049104967061783, 14245868098209934123566, 101472378935797762635619628499635817245339961, 10296643686890133479148472187437767614663729545766251948487237380959682684821520304732841 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..13.

EXAMPLE

a(1) = a(0) = 1

a(2) = a(0) + a(1) = 2

a(3) = a(0) + a(1)*a(2) = 3

a(4) = a(0) + a(1)*a(2) + a(3) = 1 + 2 + 3 = 6

a(5) = a(0) + a(1)*a(2) + a(3)*a(4) = 1 + 2 + 18 = 21

a(6) = a(0) + a(1)*a(2) + a(3)*a(4)*a(5) = 1 + 2 + 18*21 = 381

PROG

(Python)

a = [1]*99

for n in range(20):

  sum = i = 0

  k = 1

  while i<=n:

    product = 1

    for x in range(k):

      product *= a[i]

      i += 1

      if i>n: break

    sum += product

    k += 1

  a[n+1] = sum

  print(str(a[n]), end=', ')

CROSSREFS

Cf. A227363, A227364, A227365, A227366.

Sequence in context: A013155 A303224 A007501 * A270397 A278106 A015773

Adjacent sequences:  A227364 A227365 A227366 * A227368 A227369 A227370

KEYWORD

nonn

AUTHOR

Alex Ratushnyak, Jul 08 2013

STATUS

approved

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Last modified July 26 20:56 EDT 2021. Contains 346300 sequences. (Running on oeis4.)