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1, 6, 24, 82, 261, 804, 2440, 7356, 22113, 66394, 199248, 597822, 1793557, 5380776, 16142448, 48427480, 145282593, 435847950, 1307544040, 3922632330, 11767897221, 35303691916, 105911076024, 317733228372, 953199685441
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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REFERENCES
| A. H. Beiler, Recreations in the Theory of Numbers, Dover, N.Y., 1964, pp. 189, 194-196.
P. Ribenhoim, The Little Book of Big Primes, Springer-Verlag,N.Y.,1991, p. 53.
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FORMULA
| a(n)={(3^(n+3))-[2*(n^2) + 12n +19]}/8.
a(n)=sum{k=0..n, binomial(n+3, k+3)2^k} - Paul Barry (pbarry(AT)wit.ie), Aug 20 2004
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EXAMPLE
| a(n)=3a(n-1)+C(n+2,2); a(0)=1.
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CROSSREFS
| Cf. A003462 and A000340.
Sequence in context: A068711 A047790 A133474 * A118043 A166060 A124807
Adjacent sequences: A052147 A052148 A052149 * A052151 A052152 A052153
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KEYWORD
| easy,nonn
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AUTHOR
| Barry E. Williams, Jan 23 2000
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