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A339771
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a(n) = Sum_{i=0..n} Sum_{j=0..n} 2^max(i,j).
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2
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1, 7, 27, 83, 227, 579, 1411, 3331, 7683, 17411, 38915, 86019, 188419, 409603, 884739, 1900547, 4063235, 8650755, 18350083, 38797315, 81788931, 171966467, 360710147, 754974723, 1577058307, 3288334339, 6845104131, 14227079171, 29527900163, 61203283971
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,2
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REFERENCES
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Eric Billault, Walter Damin, Robert Ferréol, Rodolphe Garin, MPSI Classes Prépas - Khôlles de Maths, Exercices corrigés, Ellipses, 2012, exercice 2.22 (2), pp. 26, 43-44.
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LINKS
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FORMULA
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a(n) = (2*n-1) * 2^(n+1) + 3.
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EXAMPLE
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a(3) = 5*2^4 + 3 = 83.
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MAPLE
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seq((2*n-1)*2^(n+1)+3, n=0..40);
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MATHEMATICA
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Table[(2*n - 1)*2^(n + 1) + 3, {n, 0, 29}] (* Amiram Eldar, Dec 16 2020 *)
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PROG
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(PARI) a(n) = sum(i=0, n, sum(j=0, n, 2^max(i, j))); \\ Michel Marcus, Dec 16 2020
(Python)
a, b, c = 1, 7, 27
yield(a); yield(b)
while True:
yield c
z = 4*a - 8*b + 5*c
a, b, c = b, c, z
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CROSSREFS
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Cf. A142964 (with min instead of max).
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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