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 A285109 #17 Jun 30 2022 05:57:42 %S A285109 1,4,9,8,25,12,49,16,27,20,121,24,169,28,45,32,289,36,361,40,63,44, %T A285109 529,48,125,52,81,56,841,60,961,64,99,68,175,72,1369,76,117,80,1681, %U A285109 84,1849,88,135,92,2209,96,343,100,153,104,2809,108,275,112,171,116,3481,120,3721,124,189,128,325,132,4489,136,207 %N A285109 a(n) = n multiplied by its smallest prime factor; a(1) = 1. %H A285109 Antti Karttunen, <a href="/A285109/b285109.txt">Table of n, a(n) for n = 1..10000</a> %F A285109 a(n) = A020639(n) * n. %F A285109 Other identities. For all n >= 1: %F A285109 a(A285100(n)) = A065642(A285100(n)). [Agrees with A065642 on all terms of A285100, but not on any other points.] %t A285109 a[n_] := n * FactorInteger[n][[1, 1]]; Array[a, 100] (* _Amiram Eldar_, Jun 30 2022 *) %o A285109 (Scheme) (define (A285109 n) (* (A020639 n) n)) %o A285109 (PARI) a(n)=if(n==1, 1, n*factor(n)[1,1]); \\ _Joerg Arndt_, Oct 27 2021 %Y A285109 Cf. A005117, A020639, A032742, A253560, A285100. %Y A285109 Differs from A065642 for the first time at n=12. See A284342 for all the differing points. %K A285109 nonn %O A285109 1,2 %A A285109 _Antti Karttunen_, Apr 19 2017