A173967 Sums of two consecutive numbers that are nonsquare semiprimes.
29, 43, 67, 69, 77, 115, 171, 173, 187, 189, 237, 245, 267, 283, 285, 291, 317, 355, 403, 405, 411, 427, 429, 435, 437, 507, 597, 603, 605, 653, 669, 763, 787, 789, 891, 893, 907, 963, 1003, 1029, 1053, 1075, 1085, 1107, 1131, 1245, 1267, 1269, 1389, 1395
Offset: 1
Keywords
Examples
14=2*7; 15=3*5; 14+15=29, 21=3*7; 22=2*11; 21+22=43,..
Programs
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Mathematica
f[n_]:=Last/@FactorInteger[n]=={1,1};lst={};Do[If[f[n],If[f[n+1],AppendTo[lst,2*n+1]]],{n,7!}];lst
Formula
Extensions
New name from Andrey Zabolotskiy, Apr 07 2025