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A028401
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The (2^n+1)-th triangular number (cf. A000217).
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2
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3, 6, 15, 45, 153, 561, 2145, 8385, 33153, 131841, 525825, 2100225, 8394753, 33566721, 134242305, 536920065, 2147581953, 8590131201, 34360131585, 137439739905, 549757386753, 2199026401281, 8796099313665, 35184384671745
(list; graph; refs; listen; history; internal format)
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OFFSET
| 2,1
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COMMENTS
| Number of types of Boolean functions of n variables under a certain group.
Also the number of ordered decompositions of 2^n into 3 nonnegative integers (e.g. 2=0+0+2=0+2+0=2+0+0=1+1+0=1+0+1=0+1+1). - Tamas Kalmar-Nagy (integers(AT)kalmarnagy.com), Aug 02 2007
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REFERENCES
| I. Strazdins, Universal affine classification of Boolean functions, Acta Applic. Math. 46 (1997), 147-167.
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LINKS
| Index entries for sequences related to Boolean functions
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FORMULA
| (3/8)*2^n + (1/32)*4^n + 1. a(n) = 3*A007581(n-2) = 3/4*A060919(n-1). - Ralf Stephan (ralf(AT)ark.in-berlin.de), Aug 23 2003
a(n) = (2^n+1)(2^n+2)/2 - Tamas Kalmar-Nagy (integers(AT)kalmarnagy.com), Aug 02 2007
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CROSSREFS
| Equals 2 * A036562(n-4) - 1, n>3.
Cf. A000217.
Sequence in context: A005368 A067771 A056382 * A005655 A051169 A051610
Adjacent sequences: A028398 A028399 A028400 * A028402 A028403 A028404
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KEYWORD
| nonn,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Feb 24 2000
Simpler definition from Tamas Kalmar-Nagy (integers(AT)kalmarnagy.com), Aug 02 2007
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