A281552 - OEIS

A281552

Write n in the Elias gamma code and sum the positions where there is a '1' followed immediately to the right by a '0', counting the leftmost digit as position 1.

0, 1, 1, 2, 2, 6, 2, 3, 3, 9, 3, 8, 8, 9, 3, 4, 4, 12, 4, 11, 11, 12, 4, 10, 10, 18, 10, 11, 11, 12, 4, 5, 5, 15, 5, 14, 14, 15, 5, 13, 13, 23, 13, 14, 14, 15, 5, 12, 12, 22, 12, 21, 21, 22, 12, 13, 13, 23, 13, 14, 14, 15, 5, 6, 6, 18, 6, 17, 17, 18, 6, 16, 16, 28, 16, 17, 17, 18, 6

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,4

LINKS

Indranil Ghosh, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A049501(A171885(n)) for n > = 1.

EXAMPLE

For n = 6 , the Elias gamma code for n is '11010'. In '11010', the positions of '1' followed immediately to the right by '0' counting from left are 2 and 4. So, a(6) = 2 + 4 = 6.

For n = 10, the Elias gamma code for n is '1110010'. In '1110010', the positions of '1' followed immediately to the right by '0' counting from left are 3 and 6. So, a(10) = 3 + 6 = 9.

PROG

(Python)

def a(n):

....x= A281149(n)

....s=0

....for i in range(1, len(x)):

........if x[i-1]=="1" and x[i]=="0":

............s+=i

....return s

CROSSREFS

Cf. A049501, A171885, A281149, A281388, A281497.

Sequence in context: A357441 A134339 A162299 * A205506 A110141 A339489

Adjacent sequences: A281549 A281550 A281551 * A281553 A281554 A281555

KEYWORD

nonn,base

AUTHOR

Indranil Ghosh, Jan 24 2017

STATUS

approved