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Search: id:A075427
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| A075427 |
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a(0) = 1; a(n) = if n is even then a(n)+1 else 2*a(n). |
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+0
9
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| 1, 2, 3, 6, 7, 14, 15, 30, 31, 62, 63, 126, 127, 254, 255, 510, 511, 1022, 1023, 2046, 2047, 4094, 4095, 8190, 8191, 16382, 16383, 32766, 32767, 65534, 65535, 131070, 131071, 262142, 262143, 524286, 524287, 1048574, 1048575, 2097150, 2097151
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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a(n) = a(n-1)*(1 + n mod 2) + 1 - n mod 2; a(0)=1.
a(0)=1; for n>=1, a(2n)=2^n-1, a(2n-1)=2^n-2; a(n)=2^floor(n/2)-3/2+(-1)^n/2 - Benoit Cloitre (benoit7848c(AT)orange.fr), Sep 17 2002
a(n)=(-1)^n/2-3/2+2^(n/2)(1+sqrt(2)+(1-sqrt(2))(-1)^n) - Paul Barry (pbarry(AT)wit.ie), Apr 22 2004
Interleaved Mersenne numbers: interleaves 2*2^n-1 and 2(2*2^n-1) (A000225(n+1) and 2*A000225(n+1)). G.f.: (1+2x)/((1-x^2)(1-2x^2)); a(n)=3n(n-2)-2a(n-4); a(n)=sum{k=0..n, C(floor((n+1)/2), floor((k+1)/2)}. - Paul Barry (pbarry(AT)wit.ie), Jul 30 2004
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CROSSREFS
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Cf. A075426.
Sequence in context: A073712 A018511 A092482 this_sequence A066880 A075426 A018606
Adjacent sequences: A075424 A075425 A075426 this_sequence A075428 A075429 A075430
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KEYWORD
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nonn,nice
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AUTHOR
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Reinhard Zumkeller (reinhard.zumkeller(AT)lhsystems.com), Sep 15 2002
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