A162705 Numbers that are the sum of two reversed consecutive primes in more than one way.
582, 1026, 1032, 1038, 1092, 1122, 1128, 1134, 1152, 1296, 1644, 1716, 4152, 4344, 4602, 4932, 5068, 5562, 5808, 8706, 8862, 8988, 9012, 9036, 9066, 9264, 9726, 10110, 10308, 10326, 10342, 10398, 10638, 10698, 10764, 10794, 10806, 10866, 10912, 10944, 10998
Offset: 1
Examples
582 = R(191) + R(193) = 191 + 391 and R(683) + R(691) = 386 + 196. 1032 = R(113) + R(127) = 311 + 721 = R(613) + R(617) = 316 + 716.
Links
- Sean A. Irvine, Table of n, a(n) for n = 1..115
Programs
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Maple
read("transforms") ; A055642 := proc(n) max(1, ilog10(n)+1) ; end: A004087 := proc(n) option remember; digrev(ithprime(n)) ; end: isA162705 := proc(n) c := 0 ; for i from 1 do p := ithprime(i) ; if A055642(p) > A055642(n) then break; fi; if A004087(i)+A004087(i+1) = n then c := c+1; fi; od: RETURN(c > 1); end: for n from 1 to 10000 do if isA162705(n) then printf("%d,",n) ; fi; od: # R. J. Mathar, Jul 13 2009 -
Mathematica
Sort[Transpose[Select[Tally[FromDigits[Reverse[IntegerDigits[#[[1]]]]] + FromDigits[Reverse[IntegerDigits[#[[2]]]]]&/@Partition[Prime[Range[ 2000]],2,1]],Last[#]>1&]][[1]]] (* Harvey P. Dale, Nov 14 2012 *)
Extensions
Keyword:base plus more terms from R. J. Mathar, Jul 13 2009
Typo in first example corrected by R. J. Mathar, Jul 22 2009
More terms from Sean A. Irvine, Nov 14 2010
Comments