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A070313
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a(n) = 2^n - (2*n+1).
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9
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0, -1, -1, 1, 7, 21, 51, 113, 239, 493, 1003, 2025, 4071, 8165, 16355, 32737, 65503, 131037, 262107, 524249, 1048535, 2097109, 4194259, 8388561, 16777167, 33554381, 67108811, 134217673, 268435399, 536870853, 1073741763, 2147483585
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OFFSET
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0,5
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COMMENTS
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Binomial transform of (-1)^n! + !n. - Paul Barry, May 13 2004
This appears as the exponent in Krotov, who writes on p. 2: "in general, two extended Hamming codes can intersect in 2^(2^m - 2m - 1) elements." - Jonathan Vos Post, Jan 13 2013
Primes appear at positions n = 4, 7, 8, 28, 32, 81, 669, 1108, ... (A344781). - R. J. Mathar, Jan 22 2013
a(n) is the total number of dollars lost when using the Martingale method (bet $1, if win then continue to bet $1, if lose then double next bet) for n trials of a wager with exactly one win, n-1 losses. For the case with exactly one loss, n-1 wins, see A165900. - Max Winnick, Jun 28 2022
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LINKS
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FORMULA
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E.g.f.: (exp(x))^2 - exp(x) - 2*x*exp(x). - Paul Barry, May 13 2004
a(n) = 4*a(n-1) - 5*a(n-2) + 2*a(n-3).
G.f.: -x*(1-3*x)/((1-x)^2*(1-2*x)). (End)
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MATHEMATICA
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PROG
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(Maxima) makelist(2^n - (2*n+1), n, 0, 20); /* Martin Ettl, Jan 25 2013 */
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CROSSREFS
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KEYWORD
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sign,easy
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AUTHOR
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STATUS
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approved
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