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A086714
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a(1)=4, a(n)=a(n-1)*(a(n-1)-1)/2.
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0
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OFFSET
| 1,1
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COMMENTS
| The next two terms, a(10) and a(11), have 111 and 221 digits. [from Harvey P. Dale, June 10 2011]
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EXAMPLE
| a(2)=a(1)*(a(1)-1)/2 = 4*3/2 = 6
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MATHEMATICA
| RecurrenceTable[{a[1]==4, a[n]==(a[n-1](a[n-1]-1))/2}, a[n], {n, 10}] (* From Harvey P. Dale, June 10 2011 *)
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PROG
| (PARI) v=vector(10, i, (i==1)*4); for(i=2, 10, v[i]=v[i-1]*(v[i-1]-1)/2); v
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CROSSREFS
| Sequence in context: A073603 A064910 A191311 * A009463 A066260 A141042
Adjacent sequences: A086711 A086712 A086713 * A086715 A086716 A086717
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KEYWORD
| nonn
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AUTHOR
| Jon Perry (perry(AT)globalnet.co.uk), Jul 29 2003
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