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 A339951 #6 Jan 11 2021 23:35:17 %S A339951 1,2,4,8,64,70,280,287,0,2,16,16,32,40,280,280,560,561,3366,3367, %T A339951 20202,20205,40410,40414,0,2,16,16,32,40,0,5,30,30,150,156,156,159, %U A339951 477,483,2898,2901,8703,8709,60963,60965,0,2,0,2,4,4,8,8,40,44,0,4,4,4 %N A339951 Similar to A100787, but alternate with addition and multiplication instead. See Comments section for more information. %C A339951 We start with a(0) as 1, placing an addition sign below the digit. As such, we add 1 to a(0) to receive the next term which is 2. This time, place a multiplication sign below the new digit and double a(1) to receive a(2) which is 4. Place add under the next unused digit and add this to a(2), followed by multiply under the next a(3) and repeat. %C A339951 Unlike A100787, terms within this sequence are not strictly increasing, as the 8th digit in this sequence is a 0 where we apply multiplication. Also, the differences do not reflect the digits of this sequence, due to alternation with multiplication. The records are 1, 2, 4, 8, 64, 70, 280, 287, 280, 560, 561, 3366 ... %e A339951 1, 2, 4, 8, 64, 70, 280, 287, 0, 2, 16, ... %e A339951 + * + * +* +* +*+ *+* + * +* %e A339951 To calculate a(5), we add 6 to 64, as the 5th digit is a 6 with the add operator underneath. Thus, a(5) is 70. %e A339951 To calculate a(8), we multiply 287 by 0, as the 8th digit is a 0 with the multiply operator underneath. Thus, a(8) is 0. %Y A339951 Cf. A100787, A107974, A107975, A107976, A107977. %K A339951 base,nonn %O A339951 0,2 %A A339951 _Jamie Robert Creasey_, Dec 24 2020