A186694 Numbers ending in 1, 3, 7 or 9 such that changing any one decimal digit produces a composite number.

212159, 294001, 505447, 584141, 595631, 604171, 872897, 971767, 1062599, 1203623, 1282529, 1293671, 1524181, 1566691, 1702357, 1830661, 2017963, 2474431, 2690201, 3085553, 3326489, 3716213, 3964169, 4103917, 4134953, 4173921, 4310617, 4376703

Offset

1,1

Comments

Union of A050249 and A143641.

This sequence is infinite because Terence Tao proved that sequence A050249 is infinite.

Links

Arkadiusz Wesolowski, Table of n, a(n) for n = 1..1500

Chris Caldwell, The Prime Glossary, Weakly prime

G. L. Honaker, Jr. and Chris Caldwell, Prime Curios! 212159

G. L. Honaker, Jr. and Chris Caldwell, Prime Curios! 17171...58369 (1000-digits)

Terence Tao, A remark on primality testing and decimal expansions, Journal of the Australian Mathematical Society 91:3 (2011), pp. 405-413.

Mathematica

primeProof[n_] := Module[{d, e, isPP, num}, d=IntegerDigits[n]; isPP=True; Do[e=d; e[[i]]=j; num=FromDigits[e]; If[num != n && PrimeQ[num], isPP=False; Break[]], {i, Length[d]}, {j, 0, 9}]; isPP]; Select[Range[1, 1000000, 2], Mod[#, 5] > 0 && primeProof[#] &] (* T. D. Noe, Feb 26 2011 *)

Crossrefs

Cf. A050249, A045572, A143641.

Sequence in context: A158993 A231418 A246999 * A143641 A184383 A234829

Adjacent sequences: A186691 A186692 A186693 * A186695 A186696 A186697

Keyword

base,nonn

Author

Arkadiusz Wesolowski, Feb 25 2011

Status

approved