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 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 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

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