A179362 Number of permutations of 1..n with i-10<=p(i)<=i+2.

1, 2, 6, 18, 54, 162, 486, 1458, 4374, 13122, 39366, 117074, 348151, 1038313, 3098572, 9246640, 27592792, 82337392, 245690824, 733114816, 2187497080, 6527051536, 19475245096, 58109645152, 173387205336, 517354196145, 1543686280857

Offset

1,2

Links

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

Formula

G.f.: -(-1 + x^2 + 2*x^3 + 4*x^4 + 8*x^5 + 16*x^6 + 30*x^7 + 56*x^8 + 98*x^9 + 140*x^10 + 56*x^11 + 240*x^12 - 26*x^13 - 44*x^14 - 68*x^15 - 82*x^16 - 56*x^17 - 120*x^18 - 22*x^20 - 64*x^21 - 102*x^22 - 40*x^23 - 136*x^24 + 16*x^26 + 40*x^27 + 54*x^28 + 30*x^29 + 68*x^30 + 10*x^33 + 24*x^34 + 6*x^35 + 28*x^36 - 6*x^39 - 12*x^40 - 4*x^41 - 14*x^42 - 2*x^46 - 2*x^48 + x^52 + x^54) / (1 - x - 2*x^2 - 4*x^3 - 8*x^4 - 16*x^5 - 32*x^6 - 62*x^7 - 122*x^8 - 236*x^9 - 440*x^10 - 752*x^11 - 992*x^12 + 57*x^13 + 109*x^14 + 200*x^15 + 340*x^16 + 496*x^17 + 496*x^18 + 52*x^20 + 184*x^21 + 444*x^22 + 784*x^23 + 784*x^24 - 42*x^26 - 138*x^27 - 300*x^28 - 460*x^29 - 392*x^30 - 32*x^33 - 132*x^34 - 276*x^35 - 248*x^36 + 22*x^39 + 82*x^40 + 152*x^41 + 124*x^42 + 12*x^46 + 40*x^47 + 36*x^48 - 7*x^52 - 21*x^53 - 18*x^54 - 2*x^59 - 2*x^60 + x^65 + x^66). - Vaclav Kotesovec, Dec 01 2012

Crossrefs

Sequence in context: A179344 A179349 A179355 * A008776 A025192 A134635

Adjacent sequences: A179359 A179360 A179361 * A179363 A179364 A179365

Keyword

nonn

Author

R. H. Hardin, Jul 11 2010

Status

approved