We present a rigorous and relatively fast method for the computation of the"complexity" of a natural number (sequence A005245), and answer some "old andnew" questions related to the question in the title of this note. We alsoextend the known terms of the related sequence A005520. We put this paper in the arXiv only for possible reference. This note waswritten in 2008. It is exactly the copy we have sent to Martin N. Fuller inFebruary 11, 2009 proposing to him to join us as co-author. The ensuingcollaboration resulted in a better program and many results about thecomplexity. We have waited four years in the hope of contacting him again. Inthe mean time Iraids et al. published arXiv:1203.6462 containing some of ourresults here. Our program is similar to the one posted in the OEIS by Martin N.Fuller, but its correctness is proved here for the first time.
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机译：我们提出了一种严格且相对较快的方法来计算自然数（序列A005245）的“复杂性”，并回答了与本说明标题中的问题相关的一些“新旧问题”。我们还扩展了相关序列A005520的已知术语。我们将本文放在arXiv中仅供参考。该说明写于2008年。正是我们于2009年2月11日发送给Martin N. Fuller的副本，建议他加入我们作为合著者。随之而来的合作产生了更好的程序，并带来了许多有关复杂性的结果。我们已经等了四年，希望再次与他联系。同时，Iraids等人。已发布的arXiv：1203.6462，其中包含我们的一些结果。我们的程序与Martin N.Fuller在OEIS中发布的程序类似，但是在这里首次证明了其正确性。
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