This site is supported by donations to The OEIS Foundation.

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A001455 Number of permutations of length n with longest increasing subsequence of length 4. (Formerly M5016 N2161) 3
 1, 16, 181, 1821, 17557, 167449, 1604098, 15555398, 153315999, 1538907306, 15743413076, 164161815768, 1744049683213, 18865209953045, 207591285198178, 2321616416280982, 26362085777156567, 303635722412859447, 3544040394934246209, 41881891423602685193 (list; graph; refs; listen; history; text; internal format)
 OFFSET 4,2 REFERENCES J. M. Hammersley, A few seedings of research, in Proc. Sixth Berkeley Sympos. Math. Stat. and Prob., ed. L. M. le Cam et al., Univ. Calif. Press, 1972, Vol. I, pp. 345-394. N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence). N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS Alois P. Heinz, Table of n, a(n) for n = 4..300 R. M. Baer and P. Brock, Natural sorting over permutation spaces, Math. Comp. 22 1968 385-410. FORMULA Recurrence: (n-4)*(n+2)^2*(n+3)^2*(n+4)*(225*n^5 - 180*n^4 - 1713*n^3 + 1354*n^2 + 3326*n - 1604)*a(n) = (n+2)^2*(6750*n^9 - 4500*n^8 - 128025*n^7 + 28068*n^6 + 758512*n^5 - 184396*n^4 - 1719825*n^3 + 606292*n^2 + 573428*n - 274224)*a(n-1) - (n-1)*(61425*n^10 - 39915*n^9 - 1118034*n^8 + 644778*n^7 + 5929529*n^6 - 4355935*n^5 - 10322152*n^4 + 7841792*n^3 + 4333856*n^2 - 3087760*n - 58944)*a(n-2) + 2*(n-2)^2*(n-1)*(92250*n^8 - 88875*n^7 - 1380300*n^6 + 1835846*n^5 + 4241004*n^4 - 9250339*n^3 + 4259094*n^2 + 1427720*n - 1155840)*a(n-3) - 576*(n-3)^2*(n-2)^3*(n-1)*(225*n^5 + 945*n^4 - 183*n^3 - 2615*n^2 + 1300*n + 1408)*a(n-4). - Vaclav Kotesovec, Mar 15 2014 a(n) ~ 3 * 2^(4*n+9) / (Pi^(3/2) * n^(15/2)). - Vaclav Kotesovec, Mar 15 2014 CROSSREFS Column k=4 of A047874. Sequence in context: A016305 A218895 A016909 * A199018 A204608 A279282 Adjacent sequences:  A001452 A001453 A001454 * A001456 A001457 A001458 KEYWORD nonn AUTHOR EXTENSIONS More terms from Alois P. Heinz, Jul 01 2012 Name of the sequence clarified by Vaclav Kotesovec, Mar 18 2014 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
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified January 18 01:36 EST 2019. Contains 319260 sequences. (Running on oeis4.)