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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).
0
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.
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
KEYWORD
nonn,base
AUTHOR
J. M. Bergot and Robert Israel, Jan 21 2021
STATUS
approved