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Search: id:A162708
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| A162708 |
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Numbers that are the sum of two reversed primes in more than one way. |
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+0
1
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| 10, 14, 16, 18, 19, 20, 21, 22, 24, 27, 28, 30, 33, 34, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 54, 66, 68, 69, 70, 72, 73, 74, 75, 76, 78, 79, 81, 82, 84, 85, 86, 87, 88, 89, 90, 92, 93, 94, 95, 96, 97, 98, 99, 100, 102, 103, 104, 105, 106, 107, 108, 109
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Subsequence of A162706. - R. J. Mathar, Jul 13 2009
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EXAMPLE
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14 = R(7)+R(7)=R(3)+R(11).
28 = R(11)+R(71)=11+17 = R(41)+R(41)=14+14.
33 = 2+31 = R(2)+R(13) = 16+17 = R(61)+R(71).
36 = R(2) +R(43)=2+34 = R(5)+R(13)=5+31.
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MAPLE
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read("transforms") ; A055642 := proc(n) max(1, ilog10(n)+1) ; end:
A004087 := proc(n) option remember; digrev(ithprime(n)) ; end:
isA162708 := proc(n) c := 0 ; for i from 1 do p := ithprime(i) ; if A055642(p) > A055642(n) then break; fi; for j from 1 to i do if A004087(i)+A004087(j) = n then c := c+1; fi; od: od: RETURN(c > 1); end:
for n from 1 to 200 do if isA162708(n) then printf("%d, ", n) ; fi; od: # R. J. Mathar, Jul 13 2009
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CROSSREFS
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Sequence in context: A087247 A088711 A154774 this_sequence A067188 A092632 A055197
Adjacent sequences: A162705 A162706 A162707 this_sequence A162709 A162710 A162711
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KEYWORD
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nonn,base
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AUTHOR
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Claudio L Meller (claudiomeller(AT)gmail.com), Jul 11 2009
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EXTENSIONS
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Missing terms 14, 33, etc. inserted by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 13 2009
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