The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A171757 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A171757

Even numbers whose binary expansion begins 10.
(history; published version)

#25 by Peter Luschny at Thu Jun 24 17:11:40 EDT 2021

STATUS

reviewed

approved

#24 by Hugo Pfoertner at Thu Jun 24 17:04:56 EDT 2021

STATUS

proposed

reviewed

#23 by Michel Marcus at Thu Jun 24 16:40:20 EDT 2021

STATUS

editing

proposed

#22 by Michel Marcus at Thu Jun 24 16:40:18 EDT 2021

PROG

(PARI) isok(m) = if (!(m%2), my(b=binary(m)); (b[1]==1) && (b[2]==0)); \\ Michel Marcus, Jun 24 2021

STATUS

proposed

editing

#21 by Michael S. Branicky at Thu Jun 24 15:42:10 EDT 2021

STATUS

editing

proposed

#20 by Michael S. Branicky at Thu Jun 24 15:41:50 EDT 2021

PROG

(Python)

from itertools import count, product, takewhile

def agen(): # generator for sequence

yield 2

for digits in count(0):

for mid in product("01", repeat=digits):

yield int("10" + "".join(mid) + "0", 2)

def aupto(lim): return list(takewhile(lambda x: x <= lim, agen()))

print(aupto(180)) # Michael S. Branicky, Jun 24 2021

STATUS

proposed

editing

#19 by Georg Fischer at Thu Jun 24 15:39:20 EDT 2021

STATUS

editing

proposed

#18 by Georg Fischer at Thu Jun 24 15:33:50 EDT 2021

FORMULA

a(n) = 2*A004761(n+1). - Jon Maiga / Georg Fischer, Jun 24 2021

#17 by Georg Fischer at Thu Jun 24 15:23:53 EDT 2021

FORMULA

a(n) = A004761(n+1). - _Jon Maiga _ / Georg Fischer, Jun 24 2021

#16 by Alois P. Heinz at Thu Jun 24 15:14:44 EDT 2021

STATUS

proposed

editing