id:A070801 - OEIS Search Results

Search: id:A070801

Displaying 1-1 of 1 results found.

page 1

Largest prime <= sigma[n]: a(n)=prevprime[sigma(n)].

+0
6

3, 3, 7, 5, 11, 7, 13, 13, 17, 11, 23, 13, 23, 23, 31, 17, 37, 19, 41, 31, 31, 23, 59, 31, 41, 37, 53, 29, 71, 31, 61, 47, 53, 47, 89, 37, 59, 53, 89, 41, 89, 43, 83, 73, 71, 47, 113, 53, 89, 71, 97, 53, 113, 71, 113, 79, 89, 59, 167, 61, 89, 103, 127, 83, 139, 67, 113, 89 (list; graph; listen)

	OFFSET	`2,1`
	COMMENT	`A085379(n)<=a(n): a(A085380(n))=A085379(A085380(n)), a(A085381(n))>A085379(A085381(n)); a(A023194(n))=A000203(A023194(n)). - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jun 26 2003`
	FORMULA	`a(n)=p[Pi(sigma[n])]=A007917[A000203(n)]`
	EXAMPLE	`n=10:sigma[100]=217,prevprime[217]=211=a(100)`
	MATHEMATICA	`Table[Prime[PrimePi[DivisorSigma[1, w]]], {w, 2, 128}]`
	CROSSREFS	`Cf. A007917, A000203, A070800, A000720, A000040.` `Sequence in context: A129266 A129527 A085379 this_sequence A114753 A079316 A106481` `Adjacent sequences: A070798 A070799 A070800 this_sequence A070802 A070803 A070804`
	KEYWORD	`easy,nonn`
	AUTHOR	`Labos E. (labos(AT)ana.sote.hu), May 08 2002`

page 1

Search completed in 0.002 seconds

Last modified December 16 17:18 EST 2009. Contains 170825 sequences.

AT&T Labs Research