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 A261618 Concatenation of n, n+1 and n. 3
 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 (list; graph; refs; listen; history; text; internal format)
 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

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Last modified December 5 01:00 EST 2023. Contains 367565 sequences. (Running on oeis4.)