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A128716 Triangle where the n-th row, of n terms in order, contains consecutive multiples of n. The smallest term of row n is the smallest integer >= the largest term of row (n-1), for n >= 2. 1
1, 2, 4, 6, 9, 12, 12, 16, 20, 24, 25, 30, 35, 40, 45, 48, 54, 60, 66, 72, 78, 84, 91, 98, 105, 112, 119, 126, 128, 136, 144, 152, 160, 168, 176, 184, 189, 198, 207, 216, 225, 234, 243, 252, 261, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 363, 374, 385, 396 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

If we instead had the triangle where the smallest term of row n is the smallest integer strictly > the largest term of row (n-1), for n >= 2, then we would have sequence A033291.

LINKS

Table of n, a(n) for n=1..59.

FORMULA

T(n,k+1)=T(n,k)+n for 1<=k<n. T(n,1)=n*ceil[T(n-1,n-1)/n] for n>=2. - R. J. Mathar, Nov 01 2007

EXAMPLE

Triangle starts

1;

2, 4;

6, 9, 12;

12, 16, 20, 24;

25, 30, 35, 40, 45;

48, 54, 60, 66, 72, 78;

84, 91, 98,105,112,119,126;

128,136,144,152,160,168,176,184;

189,198,207,216,225,234,243,252,261;

MAPLE

A128716 := proc(n, k) option remember ; if n = 1 then 1 ; elif k = 1 then n*ceil(A128716(n-1, n-1)/n) ; else A128716(n, k-1)+n ; fi ; end: for n from 1 to 11 do for k from 1 to n do printf("%d, ", A128716(n, k)) ; od: od: # R. J. Mathar, Nov 01 2007

CROSSREFS

Cf. A033291.

Sequence in context: A237685 A220768 A077220 * A258934 A225600 A183422

Adjacent sequences:  A128713 A128714 A128715 * A128717 A128718 A128719

KEYWORD

easy,nonn,tabl

AUTHOR

Leroy Quet, Jun 12 2007

EXTENSIONS

More terms from R. J. Mathar, Nov 01 2007

STATUS

approved

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Last modified June 20 16:26 EDT 2019. Contains 324234 sequences. (Running on oeis4.)