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 A083991 Members of A083989 whose 10's complement is also a member of A083989. 2
 3, 7, 17, 29, 71, 83, 281, 719, 983, 997, 1637, 2309, 3701, 4493, 5507, 6299, 7691, 8363, 9161, 9803, 11003, 13163, 17117, 18371, 20807, 31181, 31793, 32693, 32843, 33617, 33893, 34211, 34673, 37277, 38453, 49409, 50591, 61547, 62723, 65327 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Diana Mecum, Table of n, a(n) for n = 1..341 EXAMPLE Leading zeros are removed before concatenation: 997 is in here because 997 is in A083989 (9973 is prime) and its 10-complement 3 is also in A083989 (37 is prime). Unlike the example of 17 and 83, the 10-complement is not a 1-to-1 relation in cases where 9 shows up as a most significant digit. 17 and 83 both are members and are each other's 10's complement. MAPLE A055120 := proc(n) local digs ; digs := ilog10(n)+1 ; 10^digs-n ; end: isA083989 := proc(n) local comp, ccat ; if isprime(n) then comp := A055120(n) ; ccat := n*10^(ilog10(comp)+1)+comp ; RETURN( isprime(ccat)) ; else false ; fi ; end: isA083991 := proc(n) local comp; if isA083989(n) then comp := A055120(n) ; RETURN( isA083989(comp) ) ; else false ; fi ; end: for n from 1 to 80000 do if isA083991(n) then printf("%d, ", n) ; fi ; od ; # R. J. Mathar, Jul 18 2007 CROSSREFS Cf. A083989, A083990. Sequence in context: A106968 A191081 A079779 * A228567 A123988 A006628 Adjacent sequences:  A083988 A083989 A083990 * A083992 A083993 A083994 KEYWORD base,nonn AUTHOR Amarnath Murthy, May 23 2003 EXTENSIONS More terms from Diana L. Mecum and R. J. Mathar, Jul 18 2007 STATUS approved

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Last modified January 24 19:34 EST 2022. Contains 350565 sequences. (Running on oeis4.)