A183871 a(n) = n + ceiling( (1/5)*n^2 ). Complement of A183870.

2, 3, 5, 8, 10, 14, 17, 21, 26, 30, 36, 41, 47, 54, 60, 68, 75, 83, 92, 100, 110, 119, 129, 140, 150, 162, 173, 185, 198, 210, 224, 237, 251, 266, 280, 296, 311, 327, 344, 360, 378, 395, 413, 432, 450, 470, 489, 509, 530, 550, 572, 593, 615, 638, 660, 684, 707, 731, 756, 780, 806, 831, 857, 884, 910, 938, 965, 993, 1022, 1050, 1080, 1109, 1139, 1170, 1200, 1232, 1263, 1295, 1328, 1360

Offset

1,1

Links

Table of n, a(n) for n=1..80.

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

Formula

a(n) = floor( (n+1)*(n+4)/5 ). [Bruno Berselli, Mar 05 2014]

Mathematica

a=5; b=-5;
Table[n+Floor[(a*n+b)^(1/2)], {n, 100}]
Table[n-1+Ceiling[(n*n-b)/a], {n, 80}]

Crossrefs

Cf. A183870.

Sequence in context: A094568 A251607 A219276 * A211542 A368052 A022955

Adjacent sequences: A183868 A183869 A183870 * A183872 A183873 A183874

Keyword

nonn,easy

Author

Clark Kimberling, Jan 07 2011

Status

approved