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A056115 a(n)=n*(n+11)/2. +0
9
0, 6, 13, 21, 30, 40, 51, 63, 76, 90, 105, 121, 138, 156, 175, 195, 216, 238, 261, 285, 310, 336, 363, 391, 420, 450, 481, 513, 546, 580, 615, 651, 688, 726, 765, 805, 846, 888, 931, 975, 1020, 1066, 1113, 1161, 1210, 1260, 1311, 1363, 1416, 1470, 1525 (list; graph; listen)
OFFSET

0,2

COMMENT

a(n)=A000096 + 4 * A001477, a(n)=A056000 + A001477 and a(n)=A056119 - A001477 - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Oct 01 2006

a(n) = A126890(n,5) for n>4. - Reinhard Zumkeller (reinhard.zumkeller(AT)lhsystems.com), Dec 30 2006

REFERENCES

A. H. Beiler, Recreations in the Theory of Numbers, Dover, N.Y., 1964, pps. 194-196.

FORMULA

G.f.(x)=x(6-5x)/(1-x)^3.

a(n)=C(n,2)-5*n ,n>=11 - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Nov 25 2006

Equals A119412/2 - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Feb 12 2007

MAPLE

a:=n->sum(floor(k+2*n/(k+n)), k=5..n): seq(a(n), n=4..53); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Oct 01 2006

[seq(binomial(n, 2)-5*n , n=11..61)]; - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Nov 25 2006

a:=n->sum(n/2, j=12..n): seq(a(n), n=11..61); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Feb 12 2007

seq((GAMMA(n+7)/GAMMA(n+5)-30)/2, n=0..50); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 23 2007

seq(sum(k, k=6..n), n=5..55); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Feb 22 2008

CROSSREFS

Cf. A055999, and A056000.

Third column of Pascal (1, 6) triangle A096956.

Cf. A000096, A056119, A056000, A001477.

Adjacent sequences: A056112 A056113 A056114 this_sequence A056116 A056117 A056118

Sequence in context: A004919 A017053 A046040 this_sequence A101247 A072212 A028872

KEYWORD

easy,nonn

AUTHOR

Barry E. Williams, Jul 04 2000

EXTENSIONS

More terms from James A. Sellers (sellersj(AT)math.psu.edu), Jul 04 2000

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Last modified May 16 23:01 EDT 2008. Contains 139884 sequences.


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