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 A102146 #15 Jan 05 2024 17:11:54 %S A102146 13,156,1520,15912,148512,2042880,14508000,162493344,1534205464, %T A102146 16203253248,144451398000,2063316971520,14903272088640, %U A102146 158269280832000,1614847741624320,17205180696931968,144444514193267496 %N A102146 a(n) = sigma(10^n - 1), where sigma(n) is the sum of positive divisors of n. %H A102146 Max Alekseyev, <a href="/A102146/b102146.txt">Table of n, a(n) for n = 1..352</a> (terms 1..322 from Ray Chandler) %H A102146 C. Caldwell, <a href="https://t5k.org/glossary/page.php?sort=SigmaFunction">Sigma function</a>. %F A102146 a(n) = A000203(A002283(n)). - _Ray Chandler_, Apr 22 2017 %t A102146 DivisorSigma[1,10^Range[20]-1] (* _Harvey P. Dale_, Jan 05 2012 *) %o A102146 (PARI) a(n) = sigma(10^n-1); \\ _Michel Marcus_, Apr 22 2017 %Y A102146 Cf. A000203, A001270, A002283, A003020, A005422, A046053, A046107, A046412, A046415, A046416, A046417, A046418, A046419, A046420, A057951, A059892, A061075, A070528, A070529, A081317, A081318, A085035, A095370, A095413, A095414, A095417, A095418, A102347, A102380, A112505, A147556, A295503, A366669. %K A102146 nonn %O A102146 1,1 %A A102146 Jun Mizuki (suzuki32(AT)sanken.osaka-u.ac.jp), Feb 14 2005