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A203157 (n-1)-st elementary symmetric function of the first n triangular numbers. 1
1, 4, 27, 288, 4500, 97200, 2778300, 101606400, 4629441600, 257191200000, 17116074360000, 1344389840640000, 123067686661920000, 12988374315396480000, 1565562975516540000000, 213751531590524928000000, 32817539834507780352000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..17.

FORMULA

Conjecture: 2*(-n+1)*a(n) +n^3*a(n-1)=0. - R. J. Mathar, Oct 01 2016

EXAMPLE

Let esf abbreviate "elementary symmetric function".  Then

0th esf of {1}:  1

1st esf of {1,3}:  1+3=4

2nd esf of {1,3,6} is 1*3+1*6+3*6=27

MATHEMATICA

f[k_] := k (k + 1)/2; t[n_] := Table[f[k], {k, 1, n}]

a[n_] := SymmetricPolynomial[n - 1, t[n]]

Table[a[n], {n, 1, 22}]  (* A203157 *)

CROSSREFS

Cf. A000217, A006472 (n-th symm. func.), A000292 (1st symm. func.).

Sequence in context: A193467 A179494 A295255 * A304340 A119820 A159599

Adjacent sequences:  A203154 A203155 A203156 * A203158 A203159 A203160

KEYWORD

nonn

AUTHOR

Clark Kimberling, Dec 29 2011

STATUS

approved

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Last modified November 15 10:08 EST 2018. Contains 317233 sequences. (Running on oeis4.)