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A191296 Least k such that k-1 and k+1 in binary representation have same number n of 0's as 1's. 2
11, 36, 140, 540, 2108, 8316, 33020, 131580, 525308, 2099196, 8392700, 33562620, 134234108, 536903676, 2147549180, 8590065660, 34360000508, 137439477756, 549756862460, 2199025352700, 8796097216508, 35184380477436, 140737505132540, 562949986975740, 2251799880794108, 9007199388958716, 36028797287399420 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

LINKS

Colin Barker, Table of n, a(n) for n = 2..1000

Index entries for linear recurrences with constant coefficients, signature (7,-14,8).

FORMULA

a(n) = 2*(2^(n-1) + 2)*(2^(n-1) - 1) for n>=3. - Nathaniel Johnston, May 30 2011

a(0)=11, a(1)=36, a(2)=140, a(3)=540, a(n)=7*a(n-1)-14*a(n-2)+8*a(n-3). - Harvey P. Dale, Jun 10 2011

G.f.: x^2*(11 - 41*x + 42*x^2 - 24*x^3) / ((1 - x)*(1 - 2*x)*(1 - 4*x)). - Colin Barker, Jan 26 2018

MATHEMATICA

Join[{11}, LinearRecurrence[{7, -14, 8}, {36, 140, 540}, 40]] (* Harvey P. Dale, Jun 10 2011 *)

PROG

(PARI) a(n)=if(n<3, 11, 2*(2^(n-1) + 2)*(2^(n-1) - 1)) \\ Charles R Greathouse IV, Jun 01 2011

(PARI) Vec(x^2*(11 - 41*x + 42*x^2 - 24*x^3) / ((1 - x)*(1 - 2*x)*(1 - 4*x)) + O(x^40)) \\ Colin Barker, Jan 26 2018

CROSSREFS

Cf. A031443 (digitally balanced numbers), A191292, A191341.

Sequence in context: A005000 A006505 A004637 * A052526 A306498 A195201

Adjacent sequences:  A191293 A191294 A191295 * A191297 A191298 A191299

KEYWORD

nonn,easy,base

AUTHOR

Juri-Stepan Gerasimov, May 29 2011

EXTENSIONS

a(11)-a(27) and recurrence from Charles R Greathouse IV, May 29 2011

STATUS

approved

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Last modified February 20 19:57 EST 2020. Contains 332084 sequences. (Running on oeis4.)