A186694 - OEIS

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

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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