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A111349
Numbers n such that the result of swapping the 4th digit and the digit 3 positions from the last digit is prime.
2
1003, 1004, 1007, 1009, 1010, 1012, 1013, 1015, 1016, 1018, 1019, 1021, 1024, 1025, 1030, 1031, 1040, 1043, 1049, 1051, 1054, 1055, 1060, 1061, 1063, 1070, 1082, 1085, 1088, 1091, 1094, 1096, 1099, 1100, 1105, 1106, 1108, 1112, 1114, 1118, 1123, 1126
OFFSET
1,1
COMMENTS
Leading zeros are dropped.
Since these numbers are just digit permutations of the primes the sequence is obviously infinite. - Charles R Greathouse IV, Oct 20 2008
PROG
(PARI) swapn(n, d) = \ d is the digit position to swap { local(j, ln, x, s, y, y2, tmp); for(x=10^(d-1), 10^(d-1)+n, s = Str(x); ln = length(s); y = eval(Vec(s)); tmp=y[d]; y[d]=y[ln-d+1]; y[ln-d+1]=tmp; y2=0; for(j=1, ln, y2+=y[j]*10^(ln-j); ); if(isprime(y2), print1(x", ")) ) }
CROSSREFS
KEYWORD
easy,nonn,base
AUTHOR
Cino Hilliard, Nov 05 2005
STATUS
approved