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Search: id:A115067
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A115067 (3*n^2-n-2)/2. +0
8
0, 4, 11, 21, 34, 50, 69, 91, 116, 144, 175, 209, 246, 286, 329, 375, 424, 476, 531, 589, 650, 714, 781, 851, 924, 1000, 1079, 1161, 1246, 1334, 1425, 1519, 1616, 1716, 1819, 1925, 2034, 2146, 2261, 2379, 2500, 2624, 2751, 2881, 3014, 3150, 3289, 3431, 3576 (list; graph; listen)
OFFSET

1,2

FORMULA

sum (n+j,j=2..n). - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Sep 12 2006

sum(igcd(n+j,n+j),j=2..n). - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Nov 05 2006

If offset = 0 then a(n) = (3*n^2 + 5*n)/2 = n(3n + 5)/2. - Omar E. Pol (info(AT)polprimos.com), May 21 2008

MAPLE

a:=n->sum(igcd(n+j, n+j), j=2..n): seq(a(n), n=1..49); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Nov 05 2006

with(finance):seq(add(cashflows([2, k, n], 0 ), k=1..n), n=0..50); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jun 22 2008

a:=n->sum(k+sum(1, k=1..n), k=2..n):seq(a(n), n=1...43); [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Aug 24 2008]

CROSSREFS

Adjacent sequences: A115064 A115065 A115066 this_sequence A115068 A115069 A115070

Sequence in context: A008052 A016438 A038427 this_sequence A009893 A027369 A008008

KEYWORD

nonn

AUTHOR

Roger Bagula (rlbagulatftn(AT)yahoo.com), Mar 01 2006

EXTENSIONS

Edited by njas, Mar 05 2006

page 1

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Last modified October 13 09:05 EDT 2008. Contains 145008 sequences.


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