My interest in numbers was sparked when I was learning the clock (cf. A034326). The next milestones were the odd and the even numbers (cf. A005408, A005843) and after some more years the primes (cf. A000040). Much much later I began to realize also the full beauty and depth of natural numbers (cf. A000027).
[I am deeply sorry to have to report that Reinhard Zumkeller passed away at the end of March 2016. He suffered from pancreatic cancer, which had already progressed to an advanced stage when it was diagnosed. He was a long-time contributor to the OEIS, and was later an editor and then a diligent and dedicated editor-in-chief. Between 2000 and 2016 he contributed over 23000 items to the OEIS. Reinhard was a great Haskell expert, and he was already ready to write a Haskell program and compute 10000 terms when I was studying a new sequence and wanted to see a graph. He will be greatly missed. Neil Sloane, July 3, 2016.]