OFFSET
0,1
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 = 0..1000
FORMULA
a(n) = ceiling((7 + sqrt(1+24*g))/2), except a(2) = 8, a(3) = 9.
MATHEMATICA
Join[{4, 6, 8, 9}, Table[Ceiling[(7+Sqrt[1+24*n])/2], {n, 4, 80}]] (* G. C. Greubel, Aug 08 2019 *)
PROG
(PARI) concat([4, 6, 8, 9], vector(80, n, ceil((7 + sqrt(1+24*(n+3)))/2) )) \\ G. C. Greubel, Aug 08 2019
(Magma) [4, 6, 8, 9] cat [Ceiling((7 + Sqrt(1+24*n))/2): n in [4..80]]; // G. C. Greubel, Aug 08 2019
(Sage) [4, 6, 8, 9]+[ceil((7 + sqrt(1+24*n))/2) for n in (4..80)] # G. C. Greubel, Aug 08 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Nov 19 2006
STATUS
approved