login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A072853 Number of permutations satisfying i-2<=p(i)<=i+6, i=1..n. 1
1, 2, 6, 18, 54, 162, 486, 1394, 3991, 11593, 33772, 98320, 286072, 831952, 2418664, 7030816, 20441944, 59441521, 172843609, 502580846, 1461344622, 4249102850, 12354982862, 35924300898, 104456501102, 303726483778, 883140022543 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

R. H. Hardin, Table of n, a(n) for n=1..400

Vladimir Baltic, On the number of certain types of strongly restricted permutations, Applicable Analysis and Discrete Mathematics Vol. 4, No 1 (April, 2010), 119-135

FORMULA

Recurrence: a(n)= a(n - 1) + 2*a(n - 2) + 4*a(n - 3) + 8*a(n - 4) + 14*a(n - 5) + 26*a(n - 6) + 44*a(n - 7) + 56*a(n - 8) - 11*a(n - 9) - 19*a(n - 10) - 28*a(n - 11) - 28*a(n - 12) - 8*a(n - 14) - 20*a(n - 15) - 20*a(n - 16) + 5*a(n - 18) + 11*a(n - 19) + 10*a(n - 20) + 2*a(n - 23) + 2*a(n - 24) - a(n - 27) - a(n - 28). G.f.: - (x^20 + x^18 - 2*x^16 - 2*x^14 - 6*x^12 - 2*x^11 - 4*x^10 - 4*x^9 + 12*x^8 + 2*x^7 + 8*x^6 + 6*x^5 + 4*x^4 + 2*x^3 + x^2 - 1)/(x^28 + x^27 - 2*x^24 - 2*x^23 - 10*x^20 - 11*x^19 - 5*x^18 + 20*x^16 + 20*x^15 + 8*x^14 + 28*x^12 + 28*x^11 + 19*x^10 + 11*x^9 - 56*x^8 - 44*x^7 - 26*x^6 - 14*x^5 - 8*x^4 - 4*x^3 - 2*x^2 - x + 1).

CROSSREFS

Cf. A002524..A002529, A072827, A072850..A072856, A079955..A080014.

Sequence in context: A182899 A160175 A072852 * A179344 A179349 A179355

Adjacent sequences:  A072850 A072851 A072852 * A072854 A072855 A072856

KEYWORD

nonn

AUTHOR

Vladimir Baltic, Jul 25 2002

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified November 18 19:06 EST 2017. Contains 294894 sequences.