A276513 - OEIS

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A276513

a(n) = the smallest number k>1 such that Sum_{p|k} 0.p = n where p runs through the prime divisors of k.

21, 16102, 281785, 275867515 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,1`
	COMMENTS	`Here 0.p means the decimal fraction obtained by writing p after the decimal point, e.g. 0.11 = 11/100.` `a(n) = the smallest number k>1 such that A276651(k) / A276652(k) = n.` `The first few values of Sum_{p\|n} 0.p are: 1/5, 3/10, 1/5, 1/2, 1/2, 7/10, 1/5, 3/10, 7/10, ...` `Conjecture: a(4) = 730610790; Sum_{p\|730610790} 0.p = 0.2 + 0.3 + 0.5 + 0.7 + 0.13 + 0.31 + 0.89 + 0.97 = 4.` `Subsequence of A005117. - Chai Wah Wu, Sep 15 2016`
	LINKS	`Table of n, a(n) for n=1..4.`
	EXAMPLE	`Number 16102 is the smallest number k with Sum_{p\|k} 0.p = 2; set of prime divisors of 16102: {2, 83, 97}; Sum_{p\|16102} 0.p = 0.2 + 0.83 + 0.97 = 2.`
	PROG	`(MAGMA) A276513:=func<n\|exists(r){k:k in[2..10^6] \| (&+[d / (10^(#Intseq(d))): d in PrimeDivisors(k)]) eq n}select r else 0>; [A276513(n): n in[1..3]]`
	CROSSREFS	`Cf. A005117, A276651, A276652, A276653, A276654, A276655.` `Sequence in context: A180769 A220643 A185557 * A167063 A115485 A172724` `Adjacent sequences: A276510 A276511 A276512 * A276514 A276515 A276516`
	KEYWORD	`nonn,base,more`
	AUTHOR	`Jaroslav Krizek, Sep 14 2016`
	EXTENSIONS	`a(4) from Chai Wah Wu, Sep 16 2016`
	STATUS	`approved`

Last modified July 21 21:14 EDT 2019. Contains 325199 sequences. (Running on oeis4.)