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 A234348 Numbers k such that both distances from k to two nearest cubes are perfect cubes. 2
 0, 1, 152, 189, 513, 728, 5859, 6832, 64008, 68913, 150605, 155736, 345744, 355167, 1062936, 1090999, 1481571, 1520848, 6653933, 6742008, 7665056, 7742709, 9667693, 9796248, 15253056, 15438185, 16582104, 16592023, 16766568, 16776487, 26201448, 26460217, 28672299 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Except a(1)=0, a(n) are numbers k such that both k-x and y-k are perfect cubes, where x and y are two nearest to k cubes: x < k <= y. LINKS Donovan Johnson, Table of n, a(n) for n = 1..1000 EXAMPLE 152 is in the sequence because the following are cubes: 152-125=27 and 216-152=64, where 125 and 216 are the nearest to 152 cubes. PROG (C) #include #include    // gcc -O3 A234348.c -lgmp int main() {   long long in=0;   mpz_t n, r, i;   mpz_init(r);   mpz_init(i);   mpz_init_set_ui(n, in);   while (in < (1ULL<<32)) {     if (mpz_root(r, n, 3) && in)  mpz_sub_ui(r, r, 1);     mpz_mul(i, r, r);     mpz_mul(i, i, r);     mpz_sub(i, n, i);     if (mpz_root(i, i, 3)) {       mpz_add_ui(r, r, 1);       mpz_mul(i, r, r);       mpz_mul(i, i, r);       mpz_sub(i, i, n);       if (mpz_root(i, i, 3))  printf("%llu, ", in);     }     mpz_add_ui(n, n, 1);     if ((++in&0xfffff)==0)  printf(".");   }   return 0; } CROSSREFS Cf. A000578, A234334. Sequence in context: A200934 A174759 A289821 * A185394 A097640 A253367 Adjacent sequences:  A234345 A234346 A234347 * A234349 A234350 A234351 KEYWORD nonn AUTHOR Alex Ratushnyak, Dec 24 2013 STATUS approved

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Last modified September 21 16:31 EDT 2021. Contains 347598 sequences. (Running on oeis4.)