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- #!/usr/bin/ruby
- # a(n) = largest prime divisor of A138957(n).
- # https://oeis.org/A138961
- # First several terms of the sequence:
- # 1, 3, 41, 617, 823, 643, 9721, 14593, 3803, 14405693, 10939223, 4156374407, 2663693, 5603770631, 1221751714624799, 287108811653770498027, 74103167823547, 11843077531813991, 726216405947772436185983423, 769725127, 18274551225153265813469
- # a(n) = A006530(A138957(n)). - ~~~~
- include("../../../factordb/auto.sf")
- func a(n) {
- 1..n -> map{.to_s.flip}.join.to_i
- }
- var bfile = File("bfile.txt").open_w.autoflush(true)
- for n in (1..10000) {
- var k = a(n)
- var row = "#{n} #{gpf(k)||1}"
- say row
- bfile.say(row)
- }
- __END__
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