

A203246


Second elementary symmetric function of the first n terms of (1,1,2,2,3,3,4,4,...).


4



1, 5, 13, 31, 58, 106, 170, 270, 395, 575, 791, 1085, 1428, 1876, 2388, 3036, 3765, 4665, 5665, 6875, 8206, 9790, 11518, 13546, 15743, 18291, 21035, 24185, 27560, 31400, 35496, 40120, 45033, 50541, 56373, 62871, 69730, 77330, 85330, 94150
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OFFSET

2,2


COMMENTS

Second subdiagonal of A246117.  Peter Bala, Aug 15 2014


LINKS

Table of n, a(n) for n=2..41.


FORMULA

Conjectural o.g.f.: x^2*(1 + 3*x + x^2 + x^3)/((1  x^2)^3*(1  x)^2).  Peter Bala, Aug 15 2014


MATHEMATICA

f[k_] := Floor[(k + 1)/2]; t[n_] := Table[f[k], {k, 1, n}]
a[n_] := SymmetricPolynomial[2, t[n]]
Table[a[n], {n, 2, 50}] (* A203246 *)


CROSSREFS

Cf. A203298, A203299, A246117.
Sequence in context: A086522 A234372 A102725 * A106985 A238742 A023261
Adjacent sequences: A203243 A203244 A203245 * A203247 A203248 A203249


KEYWORD

nonn


AUTHOR

Clark Kimberling, Dec 31 2011


STATUS

approved



