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A027916 Least k such that 1+2+...+k >= E{1,2,...,n}, where E = 2nd elementary symmetric function. 1
2, 5, 8, 13, 19, 25, 33, 42, 51, 62, 74, 86, 100, 115, 130, 147, 165, 183, 203, 224, 245, 268, 292, 316, 342, 369, 396, 425, 455, 485, 517, 550, 583, 618, 654, 690, 728, 767, 806, 847, 889, 931, 975, 1020, 1065, 1112, 1160, 1208, 1258, 1309, 1360, 1413, 1467 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

LINKS

Table of n, a(n) for n=2..54.

FORMULA

G.f.: x^2 * (x+2) / ((1-x^3)*(1-x)^2).

a(n) = A000217(n+1) + (A049347(n)-4*(n+1))/3. [From R. J. Mathar, Aug 18 2008]

a(n) = n + (n^2 mod 3) + a(n-1) (conjectured). - Jon Maiga, Aug 02 2019

MATHEMATICA

Table[Total[Table[IntegerExponent[2^(n - k) 4^k, 8], {k, 0, n}]], {n, 2, 100}] (* Fred Daniel Kline, Jun 05 2012 *)

CROSSREFS

Sequence in context: A122221 A083704 A111097 * A054254 A025216 A076059

Adjacent sequences:  A027913 A027914 A027915 * A027917 A027918 A027919

KEYWORD

nonn

AUTHOR

Clark Kimberling

EXTENSIONS

Extended according to the g.f. by R. J. Mathar, Aug 18 2008

STATUS

approved

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Last modified January 28 00:32 EST 2020. Contains 331313 sequences. (Running on oeis4.)