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 A341607 #8 Feb 20 2021 07:52:30
%S A341607 2,2,3,1,3,5,2,5,5,7,5,3,7,7,11,3,7,5,11,11,13,7,5,11,7,13,13,17,2,11,
%T A341607 7,13,11,17,17,19,3,3,13,11,17,13,19,19,23,5,5,5,17,13,19,17,23,23,29,
%U A341607 11,7,7,7,19,17,23,19,29,29,31,2,13,11,11,11,23,19,29,23,31,31,37,13,3,17,13,13,13,29,23,31,29,37,37,41
%N A341607 Square array A(n,k) = A006530(A017666(A246278(n,k))), read by falling antidiagonals.
%H A341607 <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a>
%H A341607 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%F A341607 A(n,k) = A006530(A341606(n, k)) = A006530(A017666(A246278(n,k))).
%e A341607 The top left corner of the array:
%e A341607 n= 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
%e A341607 2n= 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34
%e A341607 -----+----------------------------------------------------------------------
%e A341607 1 | 2, 2, 1, 2, 5, 3, 7, 2, 3, 5, 11, 2, 13, 1, 5, 2, 17,
%e A341607 2 | 3, 3, 5, 3, 7, 5, 11, 3, 5, 7, 13, 3, 17, 11, 7, 3, 19,
%e A341607 3 | 5, 5, 7, 5, 11, 7, 13, 5, 7, 11, 17, 7, 19, 13, 11, 5, 23,
%e A341607 4 | 7, 7, 11, 7, 13, 11, 17, 7, 11, 13, 19, 11, 23, 17, 13, 7, 29,
%e A341607 5 | 11, 11, 13, 11, 17, 13, 19, 11, 13, 17, 23, 13, 29,*11, 17, 11, 31,
%e A341607 6 | 13, 13, 17, 13, 19, 17, 23, 13, 17, 19, 29,*13, 31, 23, 19, 13, 37,
%e A341607 7 | 17, 17, 19, 17, 23, 19, 29, 17, 19, 23, 31, 19, 37, 29, 23, 17, 41,
%e A341607 8 | 19, 19, 23, 19, 29, 23, 31, 19, 23, 29, 37, 23, 41, 31, 29, 19, 43,
%e A341607 9 | 23, 23, 29, 23, 31, 29, 37, 23, 29, 31, 41, 29, 43, 37, 31, 23, 47,
%e A341607 10 | 29, 29, 31, 29, 37, 31, 41, 29, 31, 37, 43, 31, 47, 41, 37, 29, 53,
%e A341607 11 | 31, 31, 37, 31, 41, 37, 43, 31, 37, 41, 47,*31, 53, 43, 41, 31, 59,
%e A341607 12 | 37, 37, 41, 37, 43, 41, 47, 37, 41, 43, 53, 41, 59, 47, 43, 37, 61,
%e A341607 13 | 41, 41, 43, 41, 47, 43, 53, 41, 43, 47, 59, 43, 61, 53, 47, 41, 67,
%e A341607 14 | 43, 43, 47, 43, 53, 47, 59, 43, 47, 53, 61, 47, 67, 59, 53, 43, 71,
%e A341607 15 | 47, 47, 53, 47, 59, 53, 61, 47, 53, 59, 67, 53, 71, 47, 59, 47, 73,
%e A341607 16 | 53, 53, 59, 53, 61, 59, 67, 53, 59, 61, 71, 59, 73, 67, 61, 53, 79,
%e A341607 17 | 59, 59, 61, 59, 67, 61, 71, 59, 61, 67, 73, 61, 79, 71, 67, 59, 83,
%e A341607 18 | 61, 61, 67, 61, 71, 67, 73, 61, 67, 71, 79, 67, 83, 73, 71, 61, 89,
%e A341607 19 | 67, 67, 71, 67, 73, 71, 79, 67, 71, 73, 83, 71, 89, 79, 73, 67, 97,
%e A341607 20 | 71, 71, 73, 71, 79, 73, 83, 71, 73, 79, 89, 73, 97, 83, 79, 71, 101,
%e A341607 21 | 73, 73, 79, 73, 83, 79, 89, 73, 79, 83, 97, 79, 101, 89, 83, 73, 103,
%e A341607 etc.
%e A341607 Positions where columns are not strictly monotonic are marked with an asterisk (*). See the example section of A341606 for further elaboration.
%o A341607 (PARI)
%o A341607 up_to = 105;
%o A341607 A246278sq(row,col) = if(1==row,2*col, my(f = factor(2*col)); for(i=1, #f~, f[i,1] = prime(primepi(f[i,1])+(row-1))); factorback(f));
%o A341607 A006530(n) = if(n>1, vecmax(factor(n)[, 1]), 1);
%o A341607 A017666(n) = denominator(sigma(n)/n);
%o A341607 A341607sq(row,col) = A006530(A017666(A246278sq(row,col)));
%o A341607 A341607list(up_to) = { my(v = vector(up_to), i=0); for(a=1,oo, for(col=1,a, i++; if(i > up_to, return(v)); v[i] = A341607sq(col,(a-(col-1))))); (v); };
%o A341607 v341607 = A341607list(up_to);
%o A341607 A341607(n) = v341607[n];
%Y A341607 Cf. A006530, A017666, A246278, A341606, A341608, A341628.
%K A341607 nonn,tabl
%O A341607 1,1
%A A341607 _Antti Karttunen_, Feb 16 2021