A162708 Numbers that are the sum of two reversed primes in more than one way.

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

Offset

1,1

Comments

Subsequence of A162706. - R. J. Mathar, Jul 13 2009

Links

Table of n, a(n) for n=1..69.

Example

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.

Maple

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

Crossrefs

Sequence in context: A229271 A088711 A154774 * A330210 A067188 A092632

Adjacent sequences: A162705 A162706 A162707 * A162709 A162710 A162711

Keyword

nonn,base

Author

Claudio Meller, Jul 11 2009

Extensions

Missing terms 14, 33, etc. inserted by R. J. Mathar, Jul 13 2009

Status

approved