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 A380232 #20 Jan 18 2025 09:37:55
%S A380232 105105,135135,153153,165165,171171,189189,195195,207207,225225,
%T A380232 243243,255255,261261,279279,285285,297297,315315,345345,351351,
%U A380232 375375,405405,435435,459459,465465,495495,513513,525525,555555,567567,585585,615615,621621,645645,675675,705705,729729,735735,765765,783783,795795,825825,837837
%N A380232 Odd abundant numbers that are also doublets (cf. A020338).
%e A380232 a(1) = 105105 is an odd abundant number (cf. A005231) because it is and odd number and the sum of its divisors is equal to 229824 which exceeds 2*105105 = 210210. Also 105105 is a doublet (cf. A020338) because it is 105||105, that is the concatenation of 105 and 105, so 105105 is in the sequence.
%t A380232 Select[Table[FromDigits[Join[#, #] &@ IntegerDigits[n]], {n, 1, 850, 2}], DivisorSigma[-1, #] > 2 &] (* _Amiram Eldar_, Jan 18 2025 *)
%o A380232 (PARI) select(x->(sigma(x)>2*x), vector(1000, n, eval(Str(2*n-1, 2*n-1)))) \\ _Michel Marcus_, Jan 18 2025
%Y A380232 Intersection of A005231 and A020338.
%Y A380232 A subsequence is A380233.
%Y A380232 Cf. A005101, A064001.
%K A380232 nonn,base
%O A380232 1,1
%A A380232 _Omar E. Pol_, Jan 17 2025