A183865 a(n) = n - 1 + ceiling(3*(n+2)/5); complement of A183864.

1, 4, 8, 13, 19, 27, 36, 46, 57, 69, 83, 98, 114, 131, 149, 169, 190, 212, 235, 259, 285, 312, 340, 369, 399, 431, 464, 498, 533, 569, 607, 646, 686, 727, 769, 813, 858, 904, 951, 999, 1049, 1100, 1152, 1205, 1259, 1315, 1372, 1430, 1489, 1549, 1611, 1674, 1738, 1803, 1869, 1937, 2006, 2076, 2147, 2219

Offset

1,2

Links

Table of n, a(n) for n=1..60.

Index entries for linear recurrences with constant coefficients, signature (2,-1,0,0,1,-2,1).

Formula

a(n) = n-1+ceiling(3*(n+2)/5).

a(n) = 2*a(n-1) - a(n-2) + a(n-5) - 2*a(n-6) + a(n-7). - R. J. Mathar, Mar 11 2012

G.f.: x*(1 + 2*x + x^2 + x^3 + x^4 + x^5 - x^6)/((1 - x)^3*(1 + x + x^2 + x^3 + x^4)). - Stefano Spezia, Jun 01 2025

Mathematica

a=5/3; b=0;
Table[n+Floor[(a*n+b)^(1/2)], {n, 100}]
Table[n-1+Ceiling[(n*n-b)/a], {n, 60}]

Crossrefs

Cf. A183864.

Sequence in context: A034856 A365700 A362290 * A064609 A327566 A307159

Adjacent sequences: A183862 A183863 A183864 * A183866 A183867 A183868

Keyword

nonn,easy

Author

Clark Kimberling, Jan 07 2011

Status

approved