login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A328550
a(n) is the least prime p such that the next prime after p with the same last digit as p is p+10*n.
1
3, 11, 29, 313, 113, 397, 331, 269, 997, 1129, 2861, 4271, 4657, 13451, 10687, 31489, 14969, 10891, 38011, 63113, 39397, 70621, 55373, 57331, 46273, 141863, 78283, 130987, 99233, 27283, 379081, 711371, 349471, 474583, 701033, 155893, 285997, 250307, 988937, 869551, 1118441, 425417, 2385157
OFFSET
1,1
LINKS
EXAMPLE
a(3) = 29 because the next prime after 29 ending in 9 is 29+3*10=59.
MAPLE
V:= Vector(50): count:= 0:
L:= Vector(9):
p:= 2:
while count < 50 do
p:= nextprime(p);
d:= p mod 10;
if L[d] = 0 then L[d]:= p
else
m:= (p - L[d])/10;
if m <= 100 and V[m] = 0 then
V[m]:= L[d]; count:= count+1;
fi;
L[d]:= p;
fi
od:
convert(V, list);
CROSSREFS
Sequence in context: A259594 A293010 A236467 * A179234 A338051 A009183
KEYWORD
nonn,base
AUTHOR
J. M. Bergot and Robert Israel, Jan 19 2021
STATUS
approved