cp's OEIS Frontend

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

%I A214231 #10 Jul 11 2013 02:34:34
%S A214231 19,35,33,52,32,33,58,41,45,58,98,75,70,74,90,127,89,81,85,89,93,136,
%T A214231 101,105,109,113,117,139,197,156,142,146,150,154,158,183,238,182,165,
%U A214231 169,173,177,181,185,189,250,197,201,205,209,213,217,221,225,256,332
%N A214231 Sum of the four nearest neighbors of n in a right triangular type-1 spiral with positive integers.
%C A214231 Nearby numbers on diagonals are not counted as neighbors for this sequence.
%C A214231 Right triangular type-1 spiral implements the sequence Up, Right-down, Left.
%e A214231 Right triangular spiral begins:
%e A214231 56
%e A214231 55  57
%e A214231 54  29  58
%e A214231 53  28  30  59
%e A214231 52  27  11  31  60
%e A214231 51  26  10  12  32  61
%e A214231 50  25   9   2  13  33  62
%e A214231 49  24   8   1   3  14  34  63
%e A214231 48  23   7   6   5   4  15  35  64
%e A214231 47  22  21  20  19  18  17  16  36  65
%e A214231 46  45  44  43  42  41  40  39  38  37  66
%e A214231 78  77  76  75  74  73  72  71  70  69  68  67
%e A214231 The four nearest neighbors of 3 are 1, 13, 14, 5. Their sum is a(3)=33.
%Y A214231 Cf. A214230 - sum of the 8 nearest neighbors, Python program.
%Y A214231 Cf. A214227.
%K A214231 nonn,easy
%O A214231 1,1
%A A214231 _Alex Ratushnyak_, Jul 08 2012