

A114751


The following triangle contains n consecutive numbers beginning from n in ascending order if n is odd else in descending order. Sequence contains the triangle by rows.


2



1, 3, 2, 3, 4, 5, 7, 6, 5, 4, 5, 6, 7, 8, 9, 11, 10, 9, 8, 7, 6, 7, 8, 9, 10, 11, 12, 13, 15, 14, 13, 12, 11, 10, 9, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12
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OFFSET

1,2


LINKS

Table of n, a(n) for n=1..78.


FORMULA

a(n) = (3*t+2t*(1)^(t1))/2(1+(1)^t)*(j1)/2+(1(1)^t)*(j1)/2, where j = (t*t+3*t+4)/2n, t=floor((1+sqrt(8*n7))/2).  Boris Putievskiy, Jan 30 2013


EXAMPLE

1
3 2
3 4 5
7 6 5 4
5 6 7 8 9
11 10 9 8 7 6
...


MAPLE

for n from 1 to 14 do if n mod 2 = 1 then print(seq(k, k=n..2*n1)) else print(seq(2*nk, k=1..n)) fi od; # yields sequence in triangular form (Deutsch)


CROSSREFS

Cf. A114752, A114753, A210530.
Sequence in context: A091563 A161985 A035366 * A211947 A220071 A132408
Adjacent sequences: A114748 A114749 A114750 * A114752 A114753 A114754


KEYWORD

easy,nonn,tabl


AUTHOR

Amarnath Murthy, Nov 15 2005


EXTENSIONS

More terms from Emeric Deutsch, Jan 26 2006


STATUS

approved



