User blog comment:Deedlit11/Bignum Bakeoff appetizer/@comment-5529393-20140916022609/@comment-2033667-20140916042329

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int k = 9 << 99999, b = 2;

u(n) { int i = 0, o = 1; while (i++, o * b <= n) o *= b; return n ? pow(b + 1, u(i)) + u(n - o) : n; }

main { while (k = u(b++, --k)); return b; }