Subject: sequence question from an Honors Pre-Calc course

I have the following sequence:

4 16 37 58 89 145 42 20

I have no clue how to arrive at an answer. I've checked to see if it can be defined as an arithmetic or geometric series, and it can't. I've looked for primes and noticed that 37 and 89 are the only primes ... but from there I've lost. Nothing I've tried seems to work, so please help! Thanks a million!!!!


Hi Chell,

Take sum of squares of digits of previous term.

This sequence appears in a paper by A. Porges called "A set of eight numbers". It appears in The American Math Monthly, volume 52 (1945), pages 379-382.

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