A270310 Primes ending with the same decimal digit as the previous or next prime.

139, 149, 181, 191, 241, 251, 283, 293, 337, 347, 409, 419, 421, 431, 547, 557, 577, 587, 631, 641, 691, 701, 709, 719, 787, 797, 811, 821, 829, 839, 887, 907, 919, 929, 1021, 1031, 1039, 1049, 1051, 1061, 1153, 1163, 1171, 1181, 1249, 1259, 1399, 1409, 1471, 1481, 1627, 1637, 1657, 1699, 1709

Offset: 1

Author

Francois Alcover, Mar 15 2016

Keywords

• base
• easy
• nonn

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
• Robert J. Lemke Oliver and Kannan Soundararajan, Unexpected biases in the distribution of consecutive primes, arXiv:1603.03720 [math.NT], 2016.

Crossrefs

Cf. A270311.

Programs

Mathematica

Select[Prime@ Range@ 300, Function[k, Or[k == Mod[NextPrime@ #, 10], k == Mod[NextPrime[#, -1], 10]]]@ Mod[#, 10] &] (* Michael De Vlieger, Mar 15 2016 *)
Select[Partition[Prime[Range[300]],3,1],Mod[#[[2]],10]==Mod[#[[1]],10]||Mod[#[[2]],10]== Mod[#[[3]],10]&][[;;,2]] (* Harvey P. Dale, Jul 21 2023 *)

PARI

is(n)=isprime(n) && ((nextprime(n+1)-n)%10==0 || (n-precprime(n-1))%10==0) \\ Charles R Greathouse IV, Mar 15 2016

Formula

a(n) = prime(A270311(n)).

Extensions

a(15)-a(55) from Charles R Greathouse IV, Mar 15 2016