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 A239527 Numbers k^2 + (k+1)^2 that can be expressed as a sum of two squares in exactly one other way. 1
 85, 145, 221, 265, 365, 481, 545, 685, 1405, 1513, 1985, 2245, 2813, 2965, 3281, 3785, 3961, 4141, 4705, 5305, 5513, 5941, 6161, 6385, 6613, 7081, 7813, 8065, 8321, 9113, 9385, 10805, 11101, 11401, 11705, 12013, 12961, 13285, 13945, 16021, 17113, 17861, 19405 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Subsequence of A166080. LINKS Giovanni Resta, Table of n, a(n) for n = 1..10000 FORMULA Each number is of the form 2y^2 + 2y + 1. EXAMPLE 365 is in the sequence because 365 = 2^2+19^2 = 13^2+14^2; in the second representation 14-13=1. MATHEMATICA ok[n_] := 2 == Count[ PowersRepresentations[n, 2, 2], _?(! MemberQ[#, 0] &)]; Select[(2*#^2 + 2*# + 1) & /@ Range[100], ok] (* Giovanni Resta, Mar 21 2014 *) CROSSREFS Cf. A166080, A000404, A001844. Sequence in context: A027453 A259219 A273123 * A029471 A083750 A043684 Adjacent sequences: A239524 A239525 A239526 * A239528 A239529 A239530 KEYWORD nonn AUTHOR Carmine Suriano, Mar 21 2014 STATUS approved

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Last modified June 6 20:05 EDT 2023. Contains 363151 sequences. (Running on oeis4.)