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A099151 Positive integers a such that f(3a)+f(a)=concatenation of 3a and a, where f(k)=k(k+3)/2 (A000096). 0
5, 59, 599, 5999, 59999, 599999, 5999999, 59999999 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Is it difficult to prove that the sequence continues in the expected way?

LINKS

Table of n, a(n) for n=1..8.

EXAMPLE

599 is in the sequence because (3*599)(3*599+3)/2 + 599(602)/2

= 1797*1800/2 + 599*602/2 = 1797599.

CROSSREFS

Cf. A096032, A099148, A099149, A099150.

Sequence in context: A106105 A178003 A036947 * A243219 A113055 A020468

Adjacent sequences:  A099148 A099149 A099150 * A099152 A099153 A099154

KEYWORD

nonn,base

AUTHOR

John W. Layman, Sep 30 2004

EXTENSIONS

Edited by Charles R Greathouse IV, Apr 29 2010

STATUS

approved

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Last modified February 20 22:47 EST 2020. Contains 332086 sequences. (Running on oeis4.)