A030340 a(n)=(# 1's)-(# 2's) in first n terms of A003137.

1, 0, 1, 1, 2, 3, 4, 3, 2, 2, 1, 2, 1, 0, 1, 1, 1, 2, 2, 3, 4, 4, 3, 4, 5, 5, 6, 7, 8, 9, 10, 9, 10, 9, 9, 10, 9, 10, 11, 10, 9, 8, 8, 8, 7, 7, 8, 7, 7, 6, 5, 6, 6, 5, 6, 7, 6, 7, 6, 5, 4, 4, 3, 2, 3, 2, 1, 0, 1, 1, 1, 1, 2, 2, 2, 3, 4, 4, 4, 3, 4, 4, 5, 5

Offset

1,5

Comments

This sequence is nonnegative: in any group of numbers with the same number of digits, the number with a 1 in a particular position always occurs before the number with a 2 in that position. In fact, 0's only occur on the last digits of (3^N)-1, where N is an integer, not the sequence index - Larry Reeves (larryr(AT)acm.org), Sep 25 2000

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Prog

(Haskell)
a030340 n = a030340_list !! (n-1)
a030340_list = scanl1
   (\u v -> u + fromEnum (v == 1) - fromEnum (v == 2)) a003137_list
-- Reinhard Zumkeller, Feb 21 2013

Crossrefs

Cf. A030339.

Sequence in context: A260644 A073791 A350862 * A122453 A017849 A134536

Adjacent sequences: A030337 A030338 A030339 * A030341 A030342 A030343

Keyword

nonn,base

Author

Clark Kimberling

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), Sep 25 2000

Some data corrected by Reinhard Zumkeller, Feb 21 2013

Status

approved