

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 = nt(t+1)/2, t = floor((1+sqrt(8*n7))/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



