OFFSET
1,2
LINKS
Max Barrentine, Table of n, a(n) for n = 1..693
MATHEMATICA
p = Last /@ Import["https://oeis.org/A175500/b175500.txt", "Table"]; n = First[ Complement[ Range[10^4], p]] - 1; ip = 0 Range@ n; Do[If[(v = p[[i]]) <= n, ip[[v]] = i], {i, Length@p}]; ip (* Giovanni Resta, May 21 2016 *)
PROG
(PARI) ok(j, va, vs, n) = {if (vecsearch(vs, j), return (0)); for (k=1, n-1, if ((numdiv(j) == numdiv(va[k])) && (numdiv(va[k-1]) == numdiv(va[n-1])), return (0)); ); 1; }
findnew(va, vs, n) = {my(j = 1); my(vs = vecsort(va)); until (ok(j, va, vs, n), j++); j; }
listb(nn) = {my(va = [1]); for (n=2, nn, vs = vecsort(va); newa = findnew(va, vs, n); va = concat(va, newa); ); va; }
invp(v) = {for (i=1, vecmax(v), found = 0; for (k=1, #v, if (v[k] == i, found = k; break); ); if (! found, break); print1(found, ", "); ); }
lista(nn) = invp(listb(nn)); \\ Michel Marcus, May 04 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Max Barrentine, May 03 2016
STATUS
approved