Friday, October 25

Revenant gems

Éric Angelini's revenant numbers became OEIS sequence A328095. In Éric's article he mentions this "gem" found by Jean-Marc Falcoz, 62227496:

6*2*2*2*7*4*9*6 = 72576 * 62227496 = 4516222749696

Subsequently, Chai Wah Wu found 6886826188:

6*8*8*6*8*2*6*1*8*8 = 14155776 * 6886826188 = 97488368868261888

Allowing zeros in the product in any but the units position, I suggested 3691262781:

3*6*9*1*2*6*2*7*8*1 = 217728 * 3691262781 = 803691262781568

Whereupon Giovanni Resta came up with the significantly larger 774773248793:

7*7*4*7*7*3*2*4*8*7*9*3 = 348509952 * 774773248793 = 270016187747732487936