cp's OEIS Frontend

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.

A382380 Greater of twin self numbers, i.e., larger member of the pair of self numbers differing by 2.

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%I A382380 #16 Apr 25 2025 20:40:41
%S A382380 3,5,7,9,110,211,312,413,514,615,716,817,918,1111,1212,1313,1414,1515,
%T A382380 1616,1717,1818,1919,2112,2213,2314,2415,2516,2617,2718,2819,2920,
%U A382380 3113,3214,3315,3416,3517,3618,3719,3820,3921,4114,4215,4316,4417,4518,4619,4720,4821,4922,5115,5216,5317,5418
%N A382380 Greater of twin self numbers, i.e., larger member of the pair of self numbers differing by 2.
%C A382380 The number of twin self-numbers up to 10^n (for n > 2) is 9 * 10^(n-3) + 4. This has been verified up to n = 10.
%H A382380 Shyam Sunder Gupta, <a href="/A382380/b382380.txt">Table of n, a(n) for n = 1..9004</a>
%H A382380 Shyam Sunder Gupta, <a href="https://doi.org/10.1007/978-981-97-2465-9_9">On Some Marvellous Numbers of Kaprekar</a>, Exploring the Beauty of Fascinating Numbers, Springer (2025) Ch. 9, 275-315.
%F A382380 a(n) = A374101(n) + 2.
%Y A382380 Cf. A003052, A374101.
%K A382380 nonn,base
%O A382380 1,1
%A A382380 _Shyam Sunder Gupta_, Mar 23 2025