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A095225 Triangle read by rows in which the n-th row contains the n smallest triangular numbers with the least significant digits of the n-th triangular number. 2
1, 3, 153, 6, 36, 66, 10, 210, 16110, 19110, 15, 2415, 8515, 18915, 21115, 21, 3321, 7021, 18721, 21321, 39621, 28, 528, 1128, 2628, 3828, 6328, 8128, 36, 136, 16836, 18336, 21736, 23436, 73536, 76636, 45, 2145, 9045, 18145, 21945, 35245, 55945 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..43.

FORMULA

T(n,k)=b(k)*10^A055642[A000217(n)]+A000217(n) with b(1)=0, b(k)<b(k+1), 1<=k<=n. - R. J. Mathar, Aug 03 2007

EXAMPLE

In the fourth row, all numbers have the least significant digits 10=A000217(4) and are members of A000217: T(4,1)=A000217(4), T(4,2)=A000217(20), T(4,3)=A000217(179), T(4,4)=A000217(195). Triangle starts

1;

3, 153;

6, 36, 66;

10, 210, 16110, 19110;

MAPLE

A000217 := proc(n) n*(n+1)/2 ; end: A095225 := proc(nrow) local a, i, dlen; i := nrow ; a := [A000217(i)] ; dlen := ilog10(a[1])+1 ; while nops(a) < nrow do i := i+1 ; if A000217(i) mod 10^dlen = a[1] then a := [op(a), A000217(i)] ; fi ; od ; RETURN(a) ; end: seq(op(A095225(n)), n=1..10) ; # R. J. Mathar, Aug 03 2007

CROSSREFS

Cf. A095226.

Sequence in context: A287319 A189248 A209393 * A039934 A156990 A075514

Adjacent sequences:  A095222 A095223 A095224 * A095226 A095227 A095228

KEYWORD

nonn,tabl,base

AUTHOR

Amarnath Murthy, Jun 10 2004

EXTENSIONS

Corrected and extended by R. J. Mathar, Aug 03 2007

STATUS

approved

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Last modified October 20 18:25 EDT 2021. Contains 348111 sequences. (Running on oeis4.)