

A114752


a(2n)=2n, a(2n+1)=4n+1.


7



1, 2, 5, 4, 9, 6, 13, 8, 17, 10, 21, 12, 25, 14, 29, 16, 33, 18, 37, 20, 41, 22, 45, 24, 49, 26, 53, 28, 57, 30, 61, 32, 65, 34, 69, 36, 73, 38, 77, 40, 81, 42, 85, 44, 89, 46, 93, 48, 97, 50, 101, 52, 105, 54, 109, 56, 113, 58, 117, 60, 121, 62, 125, 64, 129, 66, 133, 68, 137
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OFFSET

1,2


COMMENTS

Original definition (typos corrected): The following triangle contains n consecutive numbers beginning from n in ascending order if n is odd else in descending order. 1 3 2 3 4 5 7 6 5 4 5 6 7 8 9 11 10 9 8 7 6 ... Sequence contains the leading diagonal.
The sequence satisfies a divisibility property described by E. Angelini on the SeqFan list, cf. link.  M. F. Hasler, Mar 22 2013
First difference of A014255 (shown easily from the Nurikabe property of that sequence, or by manipulating the linear recurrence representations).  Allan C. Wechsler, Oct 20 2022


LINKS



FORMULA



EXAMPLE

The triangle described in the original definition starts
1
3 2
3 4 5
7 6 5 4
5 6 7 8 9
11 10 9 8 7 6. (End)


MATHEMATICA

With[{nn=40}, Riffle[Range[1, 4nn, 4], Range[2, 2nn, 2]]] (* Harvey P. Dale, Apr 14 2017 *)


PROG



CROSSREFS



KEYWORD

nonn,easy


AUTHOR



EXTENSIONS



STATUS

approved



