This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A176970 #46 Jun 27 2024 08:42:40
%S A176970 9,25,49,121,169,289,341,361,525,529,651,765,841,961,1155,1369,1387,
%T A176970 1681,1683,1849,1935,2047,2209,2701,2809,3277,3481,3721,3751,4033,
%U A176970 4165,4305,4369,4455,4489,4681,5041,5329,5461,5525,5715,6025,6241,6643,6889,7161,7239,7921,7957,8265,8321,8925,9409,9471,9605
%N A176970 Numbers that are the product of two odd numbers x*y such that 2^x (mod y) = 2^y (mod x) = 2.
%C A176970 The numbers that are the product of two such distinct odd numbers x*y are in A337715. - _Bernard Schott_, Oct 14 2020
%e A176970 341 * 341 is a term because 2^341 mod 341 = 2.
%t A176970 okQ[x_,y_] := PowerMod[2, x, y] == PowerMod[2, y, x] == 2; n =10000; Union[Reap[Do[If[i*j < nn && okQ[i, j], Sow[i*j]], {i, 1, nn/3, 2}, {j, i, nn/3, 2}]][[2, 1]]] (* _Harvey P. Dale_, Jan 21 2011 *)
%o A176970 (PARI) isok(n) = {if ((n % 2), fordiv(n, d, if ((d >= n/d) && (lift(Mod(2, d)^(n/d)) == 2) && (lift(Mod(2, n/d)^d) == 2), return(1));););} \\ _Michel Marcus_, Sep 17 2020
%Y A176970 Cf. A001567, A179707, A179839.
%Y A176970 Cf. A337715 (subsequence).
%K A176970 nonn
%O A176970 1,1
%A A176970 _Juri-Stepan Gerasimov_, Jan 15 2011
%E A176970 Definition clarified by _T. D. Noe_, Jan 17 2011
%E A176970 Corrected and extended by _Harvey P. Dale_, Jan 21 2011