Hello Math-Fun, How high will you climb? Read one digit d at the time, starting from the first one, and extend S with the product d*(last term of S). When a zero is read, replace this product by the smallest integer not yet present in S and go on. S = 2,4,16,16,96,96,576,5184,31104,279936,1679616,8398080,58786560,352719360,1763596800,1763596800,14108774400,56435097600,169305292800,169305292800,1,4,8,56,... Integers with two or more consecutive zeros must be read carefully. I hope I did. P.-S. How I read and multiplied is visible here, on my blog: http://cinquantesignes.blogspot.com/2020/12/tapered-peaks.html Best, É.