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!)
A214227 Sum of the four nearest neighbors of n in a triangular spiral with positive integers. 3
24, 32, 20, 28, 56, 44, 64, 48, 60, 88, 60, 56, 60, 64, 68, 84, 128, 100, 92, 96, 136, 104, 108, 112, 132, 176, 132, 120, 124, 128, 132, 136, 140, 144, 148, 172, 232, 188, 172, 176, 180, 184, 240, 192, 196, 200, 204, 208, 236, 296, 236, 216, 220, 224, 228, 232, 236 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Nearby numbers on diagonals are not counted as neighbors for this sequence.

The central 1 is at ?

LINKS

Table of n, a(n) for n=1..57.

EXAMPLE

Triangular spiral begins:

.

                       43

                       / \

                      /   \

                    42 21 44

                    /  / \  \

                   /  /   \  \

                 41 20  7 22 45

                 /  /  / \  \  \

                /  /  /   \  \  \

              40 19  6  1  8 23 46

              /  /  /    \  \  \  \

             /  /  /      \  \  \  \

           39 18  5--4--3--2  9 24 47

           /  /                \  \  \

          /  /                  \  \  \

        38 17-16-15-14-13-12-11-10 25 48

        /                            \  \

       /                              \  \

     37-36-35-34-33-32-31-30-29-28-27-26 49

                                           \

                                            \

  64-63-62-61-60-59-58-57-56-55-54-53-52-51-50

.

The four nearest neighbors of 3 are 1, 4, 2, 13; their sum is a(3)=20.

CROSSREFS

Cf. A214226 (sum of the 8 nearest neighbors).

Sequence in context: A206448 A266984 A217158 * A337055 A064673 A034782

Adjacent sequences:  A214224 A214225 A214226 * A214228 A214229 A214230

KEYWORD

nonn,easy

AUTHOR

Alex Ratushnyak, Jul 07 2012

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 September 20 02:19 EDT 2021. Contains 347577 sequences. (Running on oeis4.)