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A214231 Sum of the four nearest neighbors of n in a right triangular type-1 spiral with positive integers. 2
19, 35, 33, 52, 32, 33, 58, 41, 45, 58, 98, 75, 70, 74, 90, 127, 89, 81, 85, 89, 93, 136, 101, 105, 109, 113, 117, 139, 197, 156, 142, 146, 150, 154, 158, 183, 238, 182, 165, 169, 173, 177, 181, 185, 189, 250, 197, 201, 205, 209, 213, 217, 221, 225, 256, 332 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Nearby numbers on diagonals are not counted as neighbors for this sequence.
Right triangular type-1 spiral implements the sequence Up, Right-down, Left.
LINKS
EXAMPLE
Right triangular spiral begins:
56
55 57
54 29 58
53 28 30 59
52 27 11 31 60
51 26 10 12 32 61
50 25 9 2 13 33 62
49 24 8 1 3 14 34 63
48 23 7 6 5 4 15 35 64
47 22 21 20 19 18 17 16 36 65
46 45 44 43 42 41 40 39 38 37 66
78 77 76 75 74 73 72 71 70 69 68 67
The four nearest neighbors of 3 are 1, 13, 14, 5. Their sum is a(3)=33.
CROSSREFS
Cf. A214230 - sum of the 8 nearest neighbors, Python program.
Cf. A214227.
Sequence in context: A235869 A140601 A031206 * A242847 A044064 A044445
KEYWORD
nonn,easy
AUTHOR
Alex Ratushnyak, Jul 08 2012
STATUS
approved

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Last modified May 30 16:58 EDT 2024. Contains 372971 sequences. (Running on oeis4.)