The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A257971 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A257971

First differences of A006921.
(history; published version)

#12 by N. J. A. Sloane at Mon Jun 20 13:16:23 EDT 2022

STATUS

proposed

approved

#11 by Michel Marcus at Mon Jun 20 11:51:14 EDT 2022

STATUS

editing

proposed

#10 by Michel Marcus at Mon Jun 20 11:51:06 EDT 2022

COMMENTS

a(2*n) = - A168081(n), a(2*n+1) = A168081(n+2);

a(2*n+4) = - a(2*n+1).

FORMULA

a(2*n) = - A168081(n), a(2*n+1) = A168081(n+2);

a(2*n+4) = - a(2*n+1).

STATUS

proposed

editing

#9 by Chai Wah Wu at Mon Jun 20 11:49:26 EDT 2022

STATUS

editing

proposed

#8 by Chai Wah Wu at Mon Jun 20 11:49:11 EDT 2022

PROG

(Python)

def A257971(n): return sum(int(not r & ~(n+2-r))*2**(n//2+1-r) for r in range(n//2+2)) if n & 1 else -sum(int(not r & ~(n-1-r))*2**(n//2-1-r) for r in range(n//2)) # Chai Wah Wu, Jun 20 2022

CROSSREFS

Cf. A006911, A168081.

STATUS

approved

editing

#7 by Reinhard Zumkeller at Tue Jul 14 17:07:05 EDT 2015

STATUS

editing

approved

#6 by Reinhard Zumkeller at Tue Jul 14 16:59:50 EDT 2015

COMMENTS

a(2*n) = - A168081(n), a(2*n+1) = A168081(n+2);

a(2*n+4) = - a(2*n+1).

PROG

(Haskell)

a257971 n = a257971_list !! n

a257971_list = zipWith (-) (tail a006921_list) a006921_list

CROSSREFS

Cf. A006911, A168081.

#5 by Reinhard Zumkeller at Tue Jul 14 16:59:07 EDT 2015

NAME

allocated for Reinhard ZumkellerFirst differences of A006921.

DATA

0, 2, -1, 5, -2, 8, -5, 21, -8, 34, -21, 81, -34, 128, -81, 337, -128, 546, -337, 1301, -546, 2056, -1301, 5381, -2056, 8706, -5381, 20737, -8706, 32768, -20737, 86273, -32768, 139778, -86273, 333061, -139778, 526344, -333061, 1377557, -526344, 2228770

OFFSET

0,2

LINKS

Reinhard Zumkeller, <a href="/A257971/b257971.txt">Table of n, a(n) for n = 0..1000</a>

KEYWORD

allocated

sign

AUTHOR

Reinhard Zumkeller, Jul 14 2015

STATUS

approved

editing

#4 by Reinhard Zumkeller at Tue Jul 14 16:36:43 EDT 2015

NAME

allocated for Reinhard Zumkeller

KEYWORD

recycled

allocated

#3 by R. J. Mathar at Fri Jul 10 09:56:07 EDT 2015

STATUS

editing

approved