A130975 a(n) = sum of numbers without digit 1 and with product of digits = n-th 7-smooth number.

0, 2, 3, 26, 5, 61, 7, 296, 42, 77, 942, 99, 88, 3264, 1108, 1098, 110, 13338, 55, 465, 1342, 2341, 35906, 132, 21869, 14806, 2807, 1375, 179141, 77, 1332, 16826, 17494, 45546, 1619, 394746, 3108, 376165, 1443, 192545, 5097, 53100, 49989, 2326191

Offset: 1

Author

Philippe Lallouet (philip.lallouet(AT)wanadoo.fr), Aug 23 2007

Keywords

• nonn
• base

Examples

			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.
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.
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.
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.
		

Links

• Klaus Brockhaus, Table of n, a(n) for n = 1..100

Crossrefs

Cf. A002473 (7-smooth numbers), A084796 (concatenation of prime factors of n in decreasing order).

Extensions

Edited, corrected and extended by Klaus Brockhaus, Aug 26 2007