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Search: id:A130975
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| A130975 |
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a(n) = sum of numbers without digit 1 and with product of digits = n-th 7-smooth number. |
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+0
1
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| 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
(list; graph; listen)
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OFFSET
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1,2
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LINKS
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K. Brockhaus, Table of n, a(n) for n = 1..100
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EXAMPLE
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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 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.
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CROSSREFS
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Cf. A002473 (7-smooth numbers), A084796 (concatenation of prime factors of n in decreasing order).
Sequence in context: A094998 A109586 A060371 this_sequence A002748 A056004 A032812
Adjacent sequences: A130972 A130973 A130974 this_sequence A130976 A130977 A130978
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KEYWORD
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nonn,base
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AUTHOR
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Philippe Lallouet (philip.lallouet(AT)wanadoo.fr), Aug 23 2007
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EXTENSIONS
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Edited, corrected and extended by Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Aug 26 2007
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