

A268145


Twin prime pairs concatenated to their average in decimal representation (with the lesser twin prepended and the greater twin appended).


1



345, 567, 111213, 171819, 293031, 414243, 596061, 717273, 101102103, 107108109, 137138139, 149150151, 179180181, 191192193, 197198199, 227228229, 239240241, 269270271, 281282283, 311312313, 347348349, 419420421, 431432433, 461462463, 521522523, 569570571, 599600601
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OFFSET

1,1


COMMENTS

The lesser prime of a twin prime pair is prepended and the greater prime is appended to their average (nonprime, interprime).


LINKS



EXAMPLE

a(1)=345: the lesser prime {3} of the first twin prime pair {3, 5} is prepended and the greater prime {5} is appended to their average {4}.
a(3)=111213: the lesser {11} of the 3rd twin prime pair {11, 13} is prepended and the greater prime {13} is appended to their average {12}.


MATHEMATICA

UpToN[k_]:=FromDigits//@ StringJoin//@ ToString/@ {#1, #, #+1} &/@ Select[ Table[ Prime[n]+1, {n, 2, PrimePi[k]}], PrimeQ[#+1] &]; UpToN[10000]


CROSSREFS



KEYWORD

nonn,base,easy


AUTHOR



STATUS

approved



