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 A130975 #6 Mar 30 2012 17:27:54 %S A130975 0,2,3,26,5,61,7,296,42,77,942,99,88,3264,1108,1098,110,13338,55,465, %T A130975 1342,2341,35906,132,21869,14806,2807,1375,179141,77,1332,16826,17494, %U A130975 45546,1619,394746,3108,376165,1443,192545,5097,53100,49989,2326191 %N A130975 a(n) = sum of numbers without digit 1 and with product of digits = n-th 7-smooth number. %H A130975 Klaus Brockhaus, <a href="/A130975/b130975.txt">Table of n, a(n) for n = 1..100</a> %e A130975 First 7-smooth number is 1. Sum of numbers without digit 1 and with product of digits = 1 is 0 since there are no such numbers. Hence a(1) = 0. %e A130975 Eighth 7-smooth number is 8, numbers without digit 1 and with product of digits = 8 are 8, 24, 42, 222. These sum to 296, hence a(8) = 296. %e A130975 Eleventh 7-smooth number is 12, numbers without digit 1 and with product of digits = 12 are 26, 34, 43, 62, 223, 232, 322. These sum to 942, hence a(11) = 942. %e A130975 Fifteenth 7-smooth number is 18, numbers without digit 1 and with product of digits = 18 are 29, 36, 63, 92, 233, 323, 332. These sum to 1108, hence a(15) = 1108. %Y A130975 Cf. A002473 (7-smooth numbers), A084796 (concatenation of prime factors of n in decreasing order). %K A130975 nonn,base %O A130975 1,2 %A A130975 Philippe Lallouet (philip.lallouet(AT)wanadoo.fr), Aug 23 2007 %E A130975 Edited, corrected and extended by _Klaus Brockhaus_, Aug 26 2007