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 A257253 #12 Apr 30 2015 21:44:24 %S A257253 1,1,3,1,3,10,1,3,5,21,1,3,10,14,55,1,3,5,7,11,78,1,3,10,14,22,26,136, %T A257253 1,3,5,7,11,13,17,171,1,3,10,14,22,26,34,38,253,1,3,5,21,33,39,51,57, %U A257253 69,406,1,3,10,7,11,13,17,19,23,29,465 %N A257253 Square array A(row,col) = (1/2) * (A083221(row,col+1) - A083221(row,col)): half of the first differences of each row of array constructed from the sieve of Eratosthenes. %C A257253 The array A(row,col) is read by its downwards antidiagonals as A(1,1), A(1,2), A(2,1), A(1,3), A(2,2), A(3,1), ... %H A257253 Antti Karttunen, <a href="/A257253/b257253.txt">Table of n, a(n) for n = 1..3321; the first 81 antidiagonals of the array</a> %F A257253 A(row,col) = (1/2) * (A083221(row,col+1) - A083221(row,col)). %F A257253 A(row,col) = A257251(row,col)/2. %e A257253 The top left corner of the array: %e A257253 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 %e A257253 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3 %e A257253 10, 5, 10, 5, 10, 5, 10, 5, 10, 5, 10, 5, 10, 5, 10 %e A257253 21, 14, 7, 14, 7, 14, 21, 7, 21, 14, 7, 14, 7, 14, 21 %e A257253 55, 11, 22, 11, 22, 33, 11, 33, 22, 11, 22, 33, 33, 11, 33 %e A257253 78, 26, 13, 26, 39, 13, 39, 26, 13, 26, 39, 39, 13, 39, 26 %e A257253 136, 17, 34, 51, 17, 51, 34, 17, 34, 51, 51, 17, 51, 34, 17 %e A257253 171, 38, 57, 19, 57, 38, 19, 38, 57, 57, 19, 57, 38, 19, 57 %e A257253 253, 69, 23, 69, 46, 23, 46, 69, 69, 23, 69, 46, 23, 69, 46 %e A257253 406, 29, 87, 58, 29, 58, 87, 87, 29, 87, 58, 29, 87, 58, 87 %e A257253 465, 93, 62, 31, 62, 93, 93, 31, 93, 62, 31, 93, 62, 93, 124 %e A257253 666, 74, 37, 74, 111, 111, 37, 111, 74, 37, 111, 74, 111, 148, 74 %e A257253 820, 41, 82, 123, 123, 41, 123, 82, 41, 123, 82, 123, 164, 82, 41 %e A257253 903, 86, 129, 129, 43, 129, 86, 43, 129, 86, 129, 172, 86, 43, 86 %e A257253 1081, 141, 141, 47, 141, 94, 47, 141, 94, 141, 188, 94, 47, 94, 47 %e A257253 1378, 159, 53, 159, 106, 53, 159, 106, 159, 212, 106, 53, 106, 53, 106 %e A257253 ... %o A257253 (Scheme) %o A257253 (define (A257253 n) (A257253bi (A002260 n) (A004736 n))) %o A257253 (define (A257253bi row col) (* (/ 1 2) (- (A083221bi row (+ 1 col)) (A083221bi row col)))) ;; Code for A083221bi given in A083221. %Y A257253 Transpose: A257254. %Y A257253 Cf. A083221, A257251 (same array but with terms multiplied by 2). %Y A257253 Column 1: A008837. %Y A257253 Row 4: (7/2) * A145011. %K A257253 nonn,tabl %O A257253 1,3 %A A257253 _Antti Karttunen_, Apr 29 2015