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A020962
a(n) = Sum_{k >= 1} floor((1+sqrt(2))^(n-k)).
2
1, 3, 8, 22, 55, 137, 334, 812, 1965, 4751, 11476, 27714, 66915, 161557, 390042, 941656, 2273369, 5488411, 13250208, 31988846, 77227919, 186444705, 450117350, 1086679428, 2623476229, 6333631911, 15290740076
OFFSET
1,2
LINKS
C. Kimberling, Problem 10520, Amer. Math. Mon. 103 (1996) p. 347.
FORMULA
a(n) = Sum_{i=0..n-1} A080039(i).
MATHEMATICA
Table[Sum[Floor[(1 + Sqrt[2])^(n - k)], {k, Infinity}], {n, 1, 27}] (* Alonso del Arte, Nov 30 2010 *)
CROSSREFS
Cf. A080039.
Sequence in context: A086596 A036882 A374773 * A027243 A110239 A271893
KEYWORD
nonn
EXTENSIONS
Revised Feb 03 1999. Revised Nov 30 2010.
STATUS
approved