euler45.myr


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use std

const main = {
	for var n: uint64 = 144; true; n++
		var hn = n * (n * 2 - 1)
		/* find pentagonal pn = n(3n-1)/2 */
		/* n' < 2/sqrt(3)*n */
		var i: uint64 = n * 148 / 128
		var pn = i * (i * 3 - 1) / 2
		while pn > hn
			i--
			pn = i * (i * 3 - 1) / 2
		;;
		if (pn != hn)
			continue
		;;
		/* find triangle tn = n(n+1)/2, n'<2n */
		i = n*2
		var tn = i * (i + 1) / 2
		while tn > hn
			i--
			tn = i * (i + 1) / 2
		;;
		if (tn != hn)
			continue
		;;
		std.put("n = {}, h[n] = {}\n", n, hn)
		break
	;;
}