A261618 Concatenation of n, n+1 and n.

121, 232, 343, 454, 565, 676, 787, 898, 9109, 101110, 111211, 121312, 131413, 141514, 151615, 161716, 171817, 181918, 192019, 202120, 212221, 222322, 232423, 242524, 252625, 262726, 272827, 282928, 293029, 303130, 313231, 323332, 333433, 343534, 353635, 363736

Offset

1,1

Comments

787, 9109, 111211, 131413, ... are primes. - N. J. A. Sloane, Sep 21 2015

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

a(1) = concatenation(1, 2, 1) = 121.
a(10) = concatenation(10, 11, 10) = 101110.

Maple

f:= n -> n + 10^(1+ilog10(n))*(n+1)+10^(2+ilog10(n)+ilog10(n+1))*n:
map(f, [$1..100]); # Robert Israel, Dec 29 2019

Mathematica

Map[FromDigits@ Join[#1, #2, #1] & @@ IntegerDigits[#] &, Partition[Range@ 37, 2, 1]] (* Michael De Vlieger, Dec 29 2019 *)

Prog

(PARI) a(n) = eval(concat(Str(n), concat(Str(n+1), Str(n)))); \\ Michel Marcus, Sep 10 2015
(Magma) [Seqint(Intseq(n) cat Intseq(n+1) cat Intseq(n)):n in [1..36]]; // Marius A. Burtea, Dec 29 2019

Crossrefs

Cf. A134810, A068660.

Sequence in context: A036309 A346507 A119378 * A084998 A082944 A131973

Adjacent sequences: A261615 A261616 A261617 * A261619 A261620 A261621

Keyword

nonn,base

Author

José de Jesús Camacho Medina, Sep 09 2015

Extensions

More terms from Michel Marcus, Sep 10 2015

Status

approved