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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

Table of n, a(n) for n=1..56.

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

Adjacent sequences:  A214228 A214229 A214230 * A214232 A214233 A214234

KEYWORD

nonn,easy

AUTHOR

Alex Ratushnyak, Jul 08 2012

STATUS

approved

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Last modified May 16 20:11 EDT 2022. Contains 353720 sequences. (Running on oeis4.)