A123860 a(n) = ceiling( (7 + sqrt(49+24*n))/2 ).

4, 6, 7, 8, 9, 9, 10, 10, 11, 11, 12, 12, 12, 13, 13, 13, 14, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, 18, 19, 19, 19, 19, 19, 20, 20, 20, 20, 20, 21, 21, 21, 21, 21, 21, 22, 22, 22, 22, 22, 22, 23, 23, 23, 23, 23, 23, 24, 24, 24, 24, 24, 24, 24, 25, 25, 25

Offset

-2,1

References

J. L. Gross and J. Yellen, eds., Handbook of Graph Theory, CRC Press, 2004; p. 742.

Links

G. C. Greubel, Table of n, a(n) for n = -2..1000

Maple

f:=n->ceil( (7+sqrt(49+24*n))/2 );

Mathematica

Table[Ceiling[(7+Sqrt[49+24n])/2], {n, -2, 80}] (* Harvey P. Dale, Oct 10 2013 *)

Prog

(PARI) vector(80, n, ceil((7 + sqrt(25+24*(n-2)))/2)) \\ G. C. Greubel, Aug 08 2019
(Magma) [Ceiling((7 + Sqrt(49+24*n))/2): n in [-2..80]]; // G. C. Greubel, Aug 08 2019
(Sage) [ceil((7 + sqrt(49+24*n))/2) for n in (-2..80)] # G. C. Greubel, Aug 08 2019

Crossrefs

Cf. A000703.

Sequence in context: A261491 A005670 A234948 * A122817 A074764 A101087

Adjacent sequences: A123857 A123858 A123859 * A123861 A123862 A123863

Keyword

nonn

Author

N. J. A. Sloane, Nov 19 2006

Status

approved