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1, 1, 10, 5, 42, 14, 60, 15, 110, 22, 5460, 910, 420, 60, 2040, 255, 11970, 1330, 23100, 2310, 15180, 1380, 163800, 13650, 3276, 252, 8120, 580, 286440, 19096, 314160, 19635, 3570, 210, 11515140, 639730, 103740, 5460
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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FORMULA
| a(2n) / a(2n+1)= n+1.
a(n+1)/a(n)= 2/2, 30/3, 2/4, 42/5, 2/6, 30/7, 2/8, 66/9, 2/10, 2730/11, 2/12 = A027760(n+2)/(n+1), see A141410. Numerators are also (1, 2, 6, 2, 30, 2=A141056)(n+3);
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MAPLE
| A141055 := proc(n) if n = 0 then -1; else procname(n-1)*A027760(n+2) ; end if; end proc:
A141321 := proc(n) -A141055(n)/(n+1)! ; end proc: # R. J. Mathar, Jul 08 2011
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PROG
| (PARI) a(n)=if(n, my(pr=a(n-1)); fordiv(n+2, d, if(isprime(d+1), pr*=d+1)); pr, 1)/(n+1) \\ Charles R Greathouse IV, Jul 08 2011
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CROSSREFS
| Sequence in context: A050136 A070291 A183132 * A146266 A146218 A033962
Adjacent sequences: A141318 A141319 A141320 * A141322 A141323 A141324
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KEYWORD
| nonn,uned,less
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AUTHOR
| Paul Curtz (bpcrtz(AT)free.fr), Aug 02 2008
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