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 A276580 #13 Sep 15 2016 12:22:38 %S A276580 0,0,0,0,0,0,0,0,4,0,0,0,0,3,0,0,0,4,3,0,0,0,0,0,1,4,8,0,0,0,4,1,8,3, %T A276580 16,0,0,0,0,4,5,2,0,7,0,0,0,4,2,9,3,9,18,17,0,0,0,0,2,2,0,10,12,11,2, %U A276580 0,0,0,4,0,2,8,2,17,7,23,31,0,0,0,0,3,6,7,3,11,24,0,6,6,0,0,0,4,3,3,4,0,22,20,23,10,30,16,0 %N A276580 Square array A(n,k) = A276570(A255127(n,k)), numbers in Ludic array reduced by the first element of each row. Array is read by antidiagonals A(1,1), A(1,2), A(2,1), A(1,3), A(2,2), A(3,1), ... %C A276580 The starting offset of the sequence giving the terms of square array is 2, to tally with the indexing used in A255127. The row and column indices both start from 1. %C A276580 Row 4 seems to have a period of 8: [0, 3, 3, 1, 1, 4, 2, 2], while row 5 (A276577) seems to have a period of 48. %H A276580 Antti Karttunen, <a href="/A276580/b276580.txt">Table of n, a(n) for n = 2..10441; the first 144 antidiagonals of array</a> %H A276580 <a href="/index/Si#sieve">Index entries for sequences generated by sieves</a> %e A276580 The top left 17 x 15 corner of the array: %e A276580 n A003309(n+1) = A255127(n,1). %e A276580 | | %e A276580 | | | A255127(n,k) modulo A003309(n+1) %e A276580 v v | %e A276580 1 2 |0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 %e A276580 2 3 |0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 %e A276580 3 5 |0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0 %e A276580 4 7 |0, 3, 3, 1, 1, 4, 2, 2, 0, 3, 3, 1, 1, 4, 2, 2, 0 %e A276580 5 11 |0, 0, 4, 8, 5, 9, 2, 2, 6, 3, 7, 0, 4, 4, 1, 5, 9 %e A276580 6 13 |0, 8, 3, 2, 3, 0, 8, 7, 4, 12, 4, 12, 7, 4, 3, 11, 12 %e A276580 7 17 |0, 16, 0, 9, 10, 2, 3, 0, 7, 10, 0, 3, 8, 13, 12, 0, 5 %e A276580 8 23 |0, 7, 18, 12, 17, 11, 22, 14, 2, 7, 1, 14, 2, 17, 7, 18, 10 %e A276580 9 25 |0, 17, 11, 7, 24, 20, 8, 8, 6, 21, 19, 15, 3, 3, 16, 16, 14 %e A276580 10 29 |0, 2, 23, 0, 23, 25, 0, 25, 0, 25, 2, 2, 0, 2, 6, 8, 8 %e A276580 11 37 |0, 31, 6, 10, 30, 36, 3, 21, 17, 29, 16, 14, 22, 34, 1, 13, 27 %e A276580 12 41 |0, 6, 30, 38, 25, 37, 4, 16, 5, 21, 0, 12, 22, 40, 29, 6, 24 %e A276580 13 43 |0, 16, 42, 9, 35, 38, 7, 31, 8, 1, 25, 6, 24, 5, 35, 26, 1 %e A276580 14 47 |0, 26, 13, 45, 32, 23, 10, 40, 19, 14, 21, 8, 28, 15, 0, 40, 25 %e A276580 15 53 |0, 42, 31, 14, 11, 0, 1, 0, 50, 31, 20, 29, 12, 11, 20, 1, 51 %o A276580 (Scheme) %o A276580 (define (A276580 n) (A276580bi (A002260 (- n 1)) (A004736 (- n 1)))) %o A276580 (define (A276580bi row col) (A276570 (A255127bi row col))) ;; Code for A255127bi given in A255127. %Y A276580 Cf. A003309, A255127, A272565, A276570. %Y A276580 Column 1, Rows 1 & 2: A000004. %Y A276580 Column 2: A276576. %Y A276580 Row 5: A276577. %K A276580 nonn,tabl %O A276580 2,9 %A A276580 _Antti Karttunen_, Sep 13 2016