| Displaying 1-3 of 3 results found.
page
1
5, 7, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 149, 163, 167, 173, 193
EXAMPLE
109 is in the list because it is the prime A000040(29) and can be written as 74+35=R(47)+R(53)= A004087(15)+ A004087(16).
Numbers that are the sum of two reversed consecutive primes.
+10
1
5, 8, 12, 18, 42, 48, 54, 86, 87, 92, 93, 102, 105, 108, 109, 111, 123, 124, 130, 134, 135, 136, 162, 177, 180, 246, 258, 282, 294, 303, 372, 402, 426, 434, 450, 456, 468, 470, 492, 504, 528, 542, 564, 576, 582, 588, 774, 812, 816, 828, 846, 852, 862, 866
EXAMPLE
109 is in the list because it is the sum of R(47)+R(53)=74+35=109.
MATHEMATICA
Take[Union[Total[IntegerReverse[#]]&/@Partition[Prime[Range[500]], 2, 1]], 100] (* The program is not suitable for more than 100 or so terms. *) (* Harvey P. Dale, Apr 26 2022 *)
Numbers that are the sum of two reversed primes in more than one way.
+10
0
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
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
EXTENSIONS
Missing terms 14, 33, etc. inserted by R. J. Mathar, Jul 13 2009
Search completed in 0.006 seconds
| 