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A155803
A023001 interleaved with 2*A023001 and 4*A023001.
2
0, 0, 0, 1, 2, 4, 9, 18, 36, 73, 146, 292, 585, 1170, 2340, 4681, 9362, 18724, 37449, 74898, 149796, 299593, 599186, 1198372, 2396745, 4793490, 9586980, 19173961, 38347922, 76695844, 153391689, 306783378, 613566756, 1227133513, 2454267026, 4908534052
OFFSET
0,5
COMMENTS
A033138 with three zeros prepended. - Joerg Arndt, Mar 10 2015
FORMULA
a(3n) = A023001(n). a(3n+1) = 2*A023001(n) = A125835(n). a(3n+2) = 4*A023001(n).
a(n) = a(n-3)+2^(n-3) = a(n-3)+A000079(n-3). Here, a(.) can also be one of its higher order differences.
a(n) = 2*a(n-1)+a(n-3)-2*a(n-4). G.f.: x^3/((x-1)*(2*x-1)*(1+x+x^2)). [R. J. Mathar, Jul 23 2009]
a(n) = floor(2^n/7). [Mircea Merca, Dec 22 2010]
MAPLE
A023001 := proc(n) (8^n-1)/7; end: A155803 := proc(n) RETURN( A023001(n), 2*A023001(n), 4*A023001(n)) ; end: L := [seq(A155803(n), n=0..30)] ; # R. J. Mathar, Jul 23 2009
seq(floor(2^n/7), n=0..30) # Mircea Merca, Dec 22 2010
MATHEMATICA
CoefficientList[Series[x^3/(1-2 x-x^3+2 x^4), {x, 0, 50}], x] (* Harvey P. Dale, Mar 13 2011 *)
PROG
(Magma) [Floor(2^n/7): n in [0..40]]; // Vincenzo Librandi, Sep 17 2011
CROSSREFS
Sequence in context: A119027 A145139 A033138 * A293352 A293327 A282909
KEYWORD
nonn,easy
AUTHOR
Paul Curtz, Jan 27 2009
EXTENSIONS
Edited and extended by R. J. Mathar, Jul 23 2009
STATUS
approved