A173632 - OEIS

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A173632

a(n)=sqrt((A173631(n))^2-4*P_n), where P_n is product of first n primes, if this value is integer and a(n)=0, otherwise

0, 1, 1, 1, 1, 13, 17, 1, 41, 157, 0, 0, 0, 0, 17659, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`0,6`
	COMMENTS	`a(14) appears to be the last nonzero term.`
	LINKS	`Table of n, a(n) for n=0..111.`
	MATHEMATICA	`p=4; Join[{0}, Table[p=p*Prime[n]; q=Sqrt[Ceiling[Sqrt[p]]^2-p]; If[IntegerQ[q], q, 0], {n, 200}]]`
	CROSSREFS	`Cf. A173631, A002110, A000040` `Sequence in context: A107081 A029526 A219949 * A061060 A084307 A066918` `Adjacent sequences: A173629 A173630 A173631 * A173633 A173634 A173635`
	KEYWORD	`nonn`
	AUTHOR	`Vladimir Shevelev, Nov 23 2010`
	EXTENSIONS	`Extended by T. D. Noe, Nov 23 2010`
	STATUS	`approved`

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Last modified March 28 23:19 EDT 2023. Contains 361596 sequences. (Running on oeis4.)