login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A122507 Triangular in which row n contains first n terms of A018805. 1
1, 1, 3, 1, 3, 7, 1, 3, 7, 11, 1, 3, 7, 11, 19, 1, 3, 7, 11, 19, 23, 1, 3, 7, 11, 19, 23, 35, 1, 3, 7, 11, 19, 23, 35, 43, 1, 3, 7, 11, 19, 23, 35, 43, 55, 1, 3, 7, 11, 19, 23, 35, 43, 55, 63, 1, 3, 7, 11, 19, 23, 35, 43, 55, 63, 83 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Sequence B is called a reluctant sequence of sequence A, if B is triangle array read by rows: row number k coincides with first k elements of the sequence A. Sequence A122507 is the reluctant sequence of A018805. - Boris Putievskiy, Dec 14 2012

LINKS

Table of n, a(n) for n=1..66.

Boris Putievskiy, Transformations Integer Sequences And Pairing Functions arXiv:1212.2732 [math.CO]

FORMULA

a(n) = A018805(m), where m = n-t(t+1)/2, t = floor((-1+sqrt(8*n-7))/2). - Boris Putievskiy, Dec 14 2012

EXAMPLE

1

1, 3

1, 3, 7

1, 3, 7, 11

1, 3, 7, 11, 19

1, 3, 7, 11, 19, 23

MATHEMATICA

a1 = Table[ FoldList[ Plus, 1, 2 Array[ EulerPhi, n, 2 ] ], {n, 0, 10}] Flatten[a1]

CROSSREFS

Cf. A018805.

Sequence in context: A205121 A152903 A226522 * A257258 A259325 A094250

Adjacent sequences:  A122504 A122505 A122506 * A122508 A122509 A122510

KEYWORD

nonn,tabl

AUTHOR

Roger L. Bagula, Sep 15 2006

EXTENSIONS

Edited by N. J. A. Sloane, Jun 16 2007

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 31 19:40 EDT 2020. Contains 334748 sequences. (Running on oeis4.)