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A066998
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a(0)=0; a(n) = n^2*a(n-1) + 1.
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6
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0, 1, 5, 46, 737, 18426, 663337, 32503514, 2080224897, 168498216658, 16849821665801, 2038828421561922, 293591292704916769, 49616928467130933962, 9724917979557663056553, 2188106545400474187724426
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OFFSET
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0,3
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COMMENTS
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if s(n) is a sequence defined as s(0)=x, s(n) = n^2*s(n-1) + k, then s(n) = n!^2*x + a(n)*k. - Gary Detlefs, Feb 20 2010
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LINKS
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FORMULA
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a(n) = (n!)^2*Sum_{i=1..n} 1/(i!)^2.
Sum_{n>=0} a(n) * x^n / (n!)^2 = (BesselI(0,2*sqrt(x)) - 1) / (1 - x). - Ilya Gutkovskiy, Jan 23 2021
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MATHEMATICA
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RecurrenceTable[{a[0]==0, a[n]==n^2 a[n-1]+1}, a, {n, 20}] (* Harvey P. Dale, Jan 24 2019 *)
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PROG
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(PARI) { for (n=0, 100, if (n==0, a=0, a=n^2*a + 1); write("b066998.txt", n, " ", a) ) } \\ Harry J. Smith, Apr 24 2010
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CROSSREFS
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This is the same recurrence relation as A006040 except A006040 has a(0) = 1.
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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