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”).

A287302
Primes that can be generated by the concatenation in base 4, in ascending order, of two consecutive integers read in base 10.
0
11, 103, 137, 239, 1171, 1301, 1951, 2081, 2341, 2731, 2861, 3121, 3251, 3511, 16963, 17477, 20047, 21589, 23131, 26729, 30841, 34439, 40093, 43177, 43691, 45233, 46261, 60139, 61681, 63737, 270601, 272651, 278801, 291101, 295201, 297251, 315701, 321851, 325951
OFFSET
1,1
EXAMPLE
2 and 3 in base 4 are 2 and 3 and concat(2,3) = 23 in base 10 is 11;
6 and 7 in base 4 are 12 and 13 and concat(12,13) = 1213 in base 10 is 103.
MAPLE
with(numtheory): P:= proc(q, h) local a, b, c, d, k, n; a:=convert(q+1, base, h); b:=convert(q, base, h); c:=[op(a), op(b)]; d:=0; for k from nops(c) by -1 to 1 do d:=h*d+c[k]; od; if isprime(d) then d; fi; end: seq(P(i, 4), i=1..1000);
MATHEMATICA
With[{b = 4}, Select[Map[FromDigits[Flatten@ IntegerDigits[#, b], b] &, Partition[Range@ 320, 2, 1]], PrimeQ]] (* Michael De Vlieger, May 23 2017 *)
CROSSREFS
Sequence in context: A081552 A364578 A156948 * A141915 A016133 A287833
KEYWORD
nonn,base,easy
AUTHOR
Paolo P. Lava, May 23 2017
STATUS
approved