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A225055 Irregular triangle which lists the three positions of 2*n-1 in A060819 in row n. 3
1, 2, 4, 3, 6, 12, 5, 10, 20, 7, 14, 28, 9, 18, 36, 11, 22, 44, 13, 26, 52, 15, 30, 60, 17, 34, 68, 19, 38, 76, 21, 42, 84, 23, 46, 92, 25, 50, 100, 27, 54, 108, 29, 58, 116, 31, 62, 124, 33, 66, 132, 35, 70, 140, 37, 74, 148 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

There are no multiples of 8 in the triangle.

A047592 contains a sorted list of all elements of the triangle.

The triangle is a member of a family of triangles with parameter k that list the k positions of 2*n-1: 2*n-1 in A000027 (k=1), A043547 the k=2 positions in A026741, the triangle 1,2,4,8; 3,6,12,24;... with the k=4 positions in A106609, or the triangle 1,2,4,8,16; 3,6,12,24,48;... with the k=5 positions in A106617.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

FORMULA

T(n,1) = 2*n-1. T(n,2) = 4*n-2. T(n,3) = 8*n-4.

EXAMPLE

1, 2, 4;  # 1 at A060819(1), A060819(2) and A060819(4)

3, 6, 12;  # 3 at A060819(3), A060819(6) and A060819(12)

5, 10, 20;

7, 14, 28;

9, 18, 36;

11, 22, 44;

13, 26, 52;

15, 30, 60;

MATHEMATICA

numberOfTriplets = 19; A060819 = Table[n/GCD[n, 4], {n, 1, 8*numberOfTriplets}]; Table[Position[A060819, 2*n-1], {n, 1, numberOfTriplets}] // Flatten (* Jean-Fran├žois Alcover, Apr 30 2013 *)

CROSSREFS

Cf. A147587. A042968.

Sequence in context: A134561 A258046 A334384 * A120947 A222600 A046793

Adjacent sequences:  A225052 A225053 A225054 * A225056 A225057 A225058

KEYWORD

nonn,tabf,easy

AUTHOR

Paul Curtz, Apr 26 2013

STATUS

approved

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Last modified August 7 12:18 EDT 2020. Contains 336276 sequences. (Running on oeis4.)