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%I #23 May 24 2023 12:26:51
%S 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,
%T 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,
%U 63,1,3,7,11,19,23,35,43,55,63,83
%N Triangle in which row n contains the first n terms of A018805.
%C 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
%H Boris Putievskiy, <a href="http://arxiv.org/abs/1212.2732">Transformations Integer Sequences And Pairing Functions</a>, arXiv:1212.2732 [math.CO], 2012.
%F a(n) = A018805(m), where m = n-t(t+1)/2, t = floor((-1+sqrt(8*n-7))/2). - _Boris Putievskiy_, Dec 14 2012
%e 1
%e 1, 3
%e 1, 3, 7
%e 1, 3, 7, 11
%e 1, 3, 7, 11, 19
%e 1, 3, 7, 11, 19, 23
%t a1 = Table[ FoldList[ Plus, 1, 2 Array[ EulerPhi, n, 2 ] ], {n, 0, 10}] Flatten[a1]
%t Module[{nn=20,ep},ep=Accumulate[2*EulerPhi[Range[nn]]]-1;Table[Take[ep,n],{n,nn}]]// Flatten (* _Harvey P. Dale_, May 24 2023 *)
%Y Cf. A018805.
%K nonn,tabl
%O 1,3
%A _Roger L. Bagula_, Sep 15 2006
%E Edited by _N. J. A. Sloane_, Jun 16 2007