A340800 a(n) is the least prime p = prime(k) such that the next prime with the same last digit as p is prime(k+n).

139, 19, 7, 3, 17, 11, 29, 113, 883, 397, 929, 331, 269, 4409, 10067, 14969, 10891, 22859, 57331, 57107, 78283, 41603, 46273, 27283, 527929, 623299, 906847, 425417, 1086923, 4343363, 1409851, 10943963, 10323179, 31857151, 7929491, 33747317, 5376551

Offset

1,1

Comments

a(n) = prime(k) for the first k such that A072971(k) = n.

Links

Table of n, a(n) for n=1..37.

Example

a(5) = 17 = prime(7) because the next prime after 17 with last digit 7 is 37 = prime(7+5).

Maple

N:= 30: # for a(1) to a(N)
f:= proc(n) local p, k, t;
   p:= ithprime(n);
   t:= p mod 10;
   for k from 1 do
     p:= nextprime(p);
     if p mod 10 = t then return k fi
   od
end proc:
V:= Vector(N): V[4]:= 3; count:= 1:
for n from 4 while count < N do
  v:= f(n);
  if v > 0 and v <= N and V[v] = 0 then
    V[v]:= ithprime(n); count:= count+1;
  fi
od:
convert(V, list);

Crossrefs

Cf. A072971.

Sequence in context: A005447 A261703 A266003 * A333135 A361342 A270310

Adjacent sequences: A340797 A340798 A340799 * A340801 A340802 A340803

Keyword

nonn,base

Author

J. M. Bergot and Robert Israel, Jan 21 2021

Status

approved