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 A214231 Sum of the four nearest neighbors of n in a right triangular type-1 spiral with positive integers. 2

%I

%S 19,35,33,52,32,33,58,41,45,58,98,75,70,74,90,127,89,81,85,89,93,136,

%T 101,105,109,113,117,139,197,156,142,146,150,154,158,183,238,182,165,

%U 169,173,177,181,185,189,250,197,201,205,209,213,217,221,225,256,332

%N Sum of the four nearest neighbors of n in a right triangular type-1 spiral with positive integers.

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

%C Right triangular type-1 spiral implements the sequence Up, Right-down, Left.

%e Right triangular spiral begins:

%e 56

%e 55 57

%e 54 29 58

%e 53 28 30 59

%e 52 27 11 31 60

%e 51 26 10 12 32 61

%e 50 25 9 2 13 33 62

%e 49 24 8 1 3 14 34 63

%e 48 23 7 6 5 4 15 35 64

%e 47 22 21 20 19 18 17 16 36 65

%e 46 45 44 43 42 41 40 39 38 37 66

%e 78 77 76 75 74 73 72 71 70 69 68 67

%e The four nearest neighbors of 3 are 1, 13, 14, 5. Their sum is a(3)=33.

%Y Cf. A214230 - sum of the 8 nearest neighbors, Python program.

%Y Cf. A214227.

%K nonn,easy

%O 1,1

%A _Alex Ratushnyak_, Jul 08 2012

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Last modified June 28 17:31 EDT 2022. Contains 354907 sequences. (Running on oeis4.)