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PROG
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(PARI) tsqf(n) = {sqfs = vector(n); ipos = 1; na = 2; while (ipos <= n, if (issquarefree(na), sqfs[ipos] = na; ipos++; ); na++; ); return (sqfs); }
iok(i, sqfs) = {vdig = digits(i, sqfs[1]); sdig = sum(k=1, #vdig, vdig[k]); for (j=2, #sqfs, vdig = digits(i, sqfs[j]); if (sum(k=1, #vdig, vdig[k]) != sdig, return(0)); ); return (1); }
a(n) = {sqfs = tsqf(n); ok = 0; i = 2; while(! ok, if (iok(i, sqfs), ok = 1, i++); ); return (i); } \\ Michel Marcus, May 25 2013
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