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A340257 a(n) = 2^n * (1+n*(n+1)/2). 3
1, 4, 16, 56, 176, 512, 1408, 3712, 9472, 23552, 57344, 137216, 323584, 753664, 1736704, 3964928, 8978432, 20185088, 45088768, 100139008, 221249536, 486539264, 1065353216, 2323644416, 5049942016, 10938744832, 23622320128, 50868518912, 109253230592, 234075717632 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
LINKS
FORMULA
G.f.: (4*x^2-2*x+1)/(1-2*x)^3.
E.g.f.: exp(2*x)*(2*x^2+2*x+1).
a(n) = A000079(n) + A001815(n+1).
a(n) = A000079(n) * A000124(n).
a(n) = 2*a(n-1) + n*2^n = 2*a(n-1) + A036289(n), assuming a(-1) = 1/2.
a(n) = A340298(2^n).
a(n) = 2 * A087431(n) for n > 0.
a(n) = 4 * A007466(n) for n > 0.
MAPLE
a:= n-> 2^n*(1+n*(n+1)/2):
seq(a(n), n=0..30);
MATHEMATICA
Table[2^n (1+(n(n+1))/2), {n, 0, 30}] (* or *) LinearRecurrence[{6, -12, 8}, {1, 4, 16}, 30] (* Harvey P. Dale, Jan 19 2023 *)
CROSSREFS
Partial sums of A080929.
Sequence in context: A127393 A239988 A308288 * A261386 A073388 A109634
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jan 02 2021
STATUS
approved

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Last modified June 21 20:04 EDT 2024. Contains 373559 sequences. (Running on oeis4.)