A328009 Irregular array read by rows in which row n lists the divisors of the n-th term of the sequence of amicable pairs (A259180).
1, 2, 4, 5, 10, 11, 20, 22, 44, 55, 110, 220, 1, 2, 4, 71, 142, 284, 1, 2, 4, 8, 16, 32, 37, 74, 148, 296, 592, 1184, 1, 2, 5, 10, 11, 22, 55, 110, 121, 242, 605, 1210, 1, 2, 4, 5, 10, 20, 131, 262, 524, 655, 1310, 2620, 1, 2, 4, 17, 34, 43, 68, 86, 172, 731, 1462, 2924, 1, 2, 4, 5, 10, 20, 251, 502, 1004, 1255
Offset: 1
Examples
Array begins: 1, 2, 4, 5, 10, 11, 20, 22, 44, 55, 110, 220; 1, 2, 4, 71, 142, 284; 1, 2, 4, 8, 16, 32, 37, 74, 148, 296, 592, 1184; 1, 2, 5, 10, 11, 22, 55, 110, 121, 242, 605, 1210; 1, 2, 4, 5, 10, 20, 131, 262, 524, 655, 1310, 2620; 1, 2, 4, 17, 34, 43, 68, 86, 172, 731, 1462, 2924; 1, 2, 4, 5, 10, 20, 251, 502, 1004, 1255, 2510, 5020; 1, 2, 4, 13, 26, 52, 107, 214, 428, 1391, 2782, 5564, 1, 2, 4, 8, 19, 38, 41, 76, 82, 152, 164, 328, 779, 1558, 3116, 6232; 1, 2, 4, 8, 16, 32, 199, 398, 796, 1592, 3184, 6368; ...
Crossrefs
Programs
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Mathematica
With[{s = Array[{#, DivisorSigma[1, #] - #} &, 6000]}, Flatten@ Divisors@ DeleteDuplicates[Sort /@ Select[Reverse /@ s, And[! FreeQ[s, #], UnsameQ @@ #] &]]] (* Michael De Vlieger, Oct 08 2019 *)
Comments