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A013322 Golomb-type sequence over triangular numbers. 2
1, 3, 3, 3, 6, 6, 6, 10, 10, 10, 15, 15, 15, 15, 15, 15, 21, 21, 21, 21, 21, 21, 28, 28, 28, 28, 28, 28, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 55, 55, 55, 55, 55, 55, 55, 55, 55, 55, 66, 66, 66, 66, 66, 66, 66, 66, 66, 66, 66, 66 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

All terms are triangular numbers; a(n) is length of n-th run.

It is understood that a(n) is taken to be the smallest number >= a(n-1) which is compatible with the description.

The apparent idempotence, a(a(n))=a(n), holds while n<191 and breaks after that. - Ivan Neretin, Apr 03 2015

LINKS

Ivan Neretin, Table of n, a(n) for n = 1..10000

MAPLE

A:= 1, 3, 3, 3:

for n from 4 to 30 do

  t:= n*(n-1)/2;

  A:= A, t$A[n-1]

od:

A; # Robert Israel, Apr 03 2015

MATHEMATICA

a = {1, 3, 3, 3}; Do[a = Join[a, Array[i(i+1)/2&, a[[i]]]], {i, 3, 11}]; a (* Ivan Neretin, Apr 03 2015 *)

CROSSREFS

Cf. A001462.

Sequence in context: A057944 A281258 A080607 * A211534 A219816 A177821

Adjacent sequences:  A013319 A013320 A013321 * A013323 A013324 A013325

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

STATUS

approved

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Last modified December 10 20:48 EST 2017. Contains 295856 sequences.