A030339 -id:A030339 - cp's OEIS frontend

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

Clark Kimberling

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

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

Cf. A030339.

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

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

Some data corrected by Reinhard Zumkeller, Feb 21 2013

cp's OEIS Frontend

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

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