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A130665 a(n) = Sum_{k=1..n} 3^wt(k), where wt() = A000120(). +0
7
1, 4, 7, 16, 19, 28, 37, 64, 67, 76, 85, 112, 121, 148, 175, 256, 259, 268, 277, 304, 313, 340, 367, 448, 457, 484, 511, 592, 619, 700, 781, 1024, 1027, 1036, 1045, 1072, 1081, 1108, 1135, 1216, 1225, 1252, 1279, 1360, 1387, 1468, 1549, 1792, 1801, 1828, 1855 (list; graph; listen)
OFFSET

0,2

REFERENCES

D. E. Knuth, Problem submitted to Amer. Math. Monthly, Jun 18 2007.

FORMULA

With a different offset: a(1) = 1; a(n) = max { 3*a(k)+a(n-k) | 1 <= k <= n/2 }, for n>1.

a(2n+1) = 4a(n) and a(2n) = 3a(n-1)+a(n).

MAPLE

u:=3; a[1]:=1; M:=30; for n from 1 to M do a[2*n] := (u+1)*a[n]; a[2*n+1] := u*a[n] + a[n+1]; od; t1:=[seq( a[n], n=1..2*M )]; # Gives sequence with a different offset

CROSSREFS

Cf. A006046, A116520, A130667.

Partial sums of A048883. - David Applegate, Jun 11 2009.

Adjacent sequences: A130662 A130663 A130664 this_sequence A130666 A130667 A130668

Sequence in context: A166700 A160715 A160120 this_sequence A101534 A110933 A067398

KEYWORD

nonn

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com), based on a message from D. E. Knuth, Jun 23 2007

EXTENSIONS

Simpler definition (and new offset) from David Applegate, Jun 11 2009

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Last modified November 9 12:23 EST 2009. Contains 166233 sequences.


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