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A100792 Group the natural numbers so that the n-th group contains n(n+1)/2 = T(n) terms: (1), (2,3,4), (5,6,7,8,9,10), (11,12,13,14,15,16,17,18,19,20),(21,22,23,24,25,26,27,28,29,30,31,32,33,34,35),... The r-th term of the n-th row of the following triangle is the sum of the next r terms of the n-th group, e.g. third row is (5),(6+7), (8+9+10) or 5,13,27. Sequence contains the triangle read by rows. 1
1, 2, 7, 5, 13, 27, 11, 25, 45, 74, 21, 45, 75, 114, 165, 36, 75, 120, 174, 240, 321, 57, 117, 183, 258, 345, 447, 567, 85, 173, 267, 370, 485, 615, 763, 932, 121, 245, 375, 514, 665, 831, 1015, 1220, 1449, 166, 335, 510, 694, 890, 1101, 1330, 1580, 1854, 2155 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..55.

EXAMPLE

1

2 7

5 13 27

11 25 45 74

21 45 75 114 165

...

CROSSREFS

Cf. A100791.

Sequence in context: A294075 A165355 A038004 * A096037 A286379 A233248

Adjacent sequences:  A100789 A100790 A100791 * A100793 A100794 A100795

KEYWORD

easy,nonn,tabl

AUTHOR

Amarnath Murthy, Dec 01 2004

EXTENSIONS

More terms from Ray Chandler, Dec 10 2004

STATUS

approved

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Last modified May 27 12:45 EDT 2020. Contains 334657 sequences. (Running on oeis4.)