cp's OEIS Frontend

A365873 The "triple commas" sequence, a variant of A121805. See the Comments and Example sections for detailed explanations.

%I A365873 #7 Sep 25 2023 08:52:59
%S A365873 1,43,136,325,487,718,985,1138,1381,1414,1537,1750,1753,1846,2032,
%T A365873 2098,2344,2470,2476,2662,2728,2974,3103,3202,3271,3310,3319,3598,
%U A365873 3847,4069,4351,4393,4495,4657,4879,5164,5299,5584,5719,6007,6235,6403,6511,6559,6847,7078,7339,7630,7651,7702,7783,7894
%N A365873 The "triple commas" sequence, a variant of A121805. See the Comments and Example sections for detailed explanations.
%C A365873 The pair of digits adjacent to the comma between two terms forms an integer that is the third of the difference between the said terms. This is the lexicographically earliest sequence with this property. It will stop at some point, but when?
%H A365873 Eric Angelini, <a href="https://cinquantesignes.blogspot.com/2023/09/commas-variants.html">Commas variants</a>, personal blog, Sept 2023.
%e A365873 a(1) = 1 and a(2) = 43 are separated by 42 units, and 42 is 3*14 (or 1,4);
%e A365873 a(2) = 43 and a(3) = 136 are separated by 93 units, and 93 is 3*31 (or 3,1);
%e A365873 a(3) = 136 and a(4) = 325 are separated by 189 units, and 189 is 3*63 (or 6,3);
%e A365873 a(4) = 325 and a(5) = 487 are separated by 162 units, and 162 is 3*54 (or 5,4); etc.
%t A365873 a[1]=1;a[n_]:=a[n]=(k=a[n-1];While[3FromDigits@Join[{Mod[a[n-1],10]},{First@IntegerDigits@k}]!=k-a[n-1],k++];k);Array[a,70]
%Y A365873 Cf. A121805 (the original 2006 sequence), A365872, A365874, A365875.
%K A365873 base,nonn,fini
%O A365873 1,2
%A A365873 _Eric Angelini_ and _Giorgos Kalogeropoulos_, Sep 21 2023