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A328199 Triples (a,b,c) such that (a+b+c)^3 = concat(a,b,c), a, b, c > 0, ordered by size of this value. 3
5, 1, 2, 9, 11, 25, 418, 1062, 131, 878, 2442, 1125, 938, 2422, 1184, 1212, 1388, 2349, 1287, 1113, 2649, 1623, 2457, 1375, 1713, 2377, 1464, 3689, 1035, 2448, 7890, 10706, 1312, 17147, 18793, 19616, 22072, 11858, 26504, 47051, 15775, 14952 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The sequence can be considered as a table with rows of length 3, row(n) = a(3n-2 .. 3n).

A variant of Kaprekar and pseudo-Kaprekar triples, cf. A006887 and A060768.

See A328198 and A328200 (sequence of the values a+b+c and concatenated triples) for more information.

LINKS

Giovanni Resta, Table of n, a(n) for n = 1..717

NĂºmeros y algo mas, 9 + 11+ 25 = 91125^(1/3) etc, post on facebook.com, Sep 30 2019.

EXAMPLE

5+1+2 = 512^(1/3) = 8,

9+11+25 = 91125^(1/3) = 45,

418+1062+131 = (4181062131)^(1/3) = 1611, ...

PROG

(PARI) is(n, Ln=A055642(n), n3=n^3, Ln3=A055642(n3))={my(ab, c); for(Lc=Ln3-2*Ln, Ln, [ab, c]=divrem(n3, 10^Lc); n-c<10^(Ln-1) || c < 10^(Lc-1) || for( Lb=Ln3-Ln-Lc, Ln, vecsum(divrem(ab, 10^Lb)) == n-c && ab%10^Lb>=10^(Lb-1)&& return(concat(divrem(ab, 10^Lb)~, c))))} \\ A055642(n)=logint(n, 10)+1 = #digits(n)

for( Ln=1, oo, for( n=10^(Ln-1), 10^Ln-1, (t=is(n, Ln))&& print1(t", ")))

CROSSREFS

Cf. A328198 (row sums), A328200 (rows concatenated), A006887 & A291461 (Kaprekar numbers), A060768 (pseudo Kaprekar numbers); A000578 (the cubes), A055642 (number of digits of n).

Sequence in context: A021665 A226613 A274989 * A289690 A088781 A085608

Adjacent sequences:  A328196 A328197 A328198 * A328200 A328201 A328202

KEYWORD

nonn,base,tabf

AUTHOR

M. F. Hasler, Oct 07 2019

STATUS

approved

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Last modified August 15 07:14 EDT 2022. Contains 356128 sequences. (Running on oeis4.)