id:A131866 - OEIS Search Results

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Distance of n-th semiprime to nearest square.

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0, 2, 0, 1, 2, 1, 4, 3, 0, 1, 3, 2, 1, 2, 3, 3, 0, 2, 6, 7, 6, 2, 1, 5, 7, 4, 1, 4, 5, 6, 9, 7, 6, 5, 6, 10, 6, 3, 2, 0, 1, 2, 8, 11, 10, 3, 2, 1, 1, 2, 11, 11, 10, 8, 3, 0, 8, 9, 13, 11, 9, 2, 5, 6, 7, 9, 10, 13, 12, 11, 10, 8, 7, 6, 4, 1, 10, 12, 9, 7, 3, 2, 3, 6, 9, 11, 15, 11, 2, 0, 2, 6, 9, 10, 12 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`This to semiprimes A001358 as A047972 is to primes A000040.` `For each semiprime, find the closest square (preceding or succeeding); subtract, take absolute value.`
	FORMULA	`a(n)=A053188(A001358(n)) (corrected by R. J. Mathar, Nov 19 2007).`
	EXAMPLE	`a(1) = 0 because the 1st semiprime is 4, which is a square.` `a(2) = 2 because the 2nd semiprime is 6 and \|6-4\| = 2 where 4 is the nearest square to 6.` `a(3) = 0 because the 3rd semiprime is 9, which is a square.` `a(4) = 1 because the 4th semiprime is 10 and \|10-9\| = 1 where 9 is the nearest square to 10.`
	CROSSREFS	`Cf. A001358, A047972, A053188.` `Sequence in context: A020513 A029276 A109248 this_sequence A036862 A094238 A127793` `Adjacent sequences: A131863 A131864 A131865 this_sequence A131867 A131868 A131869`
	KEYWORD	`easy,nonn`
	AUTHOR	`Jonathan Vos Post (jvospost3(AT)gmail.com), Oct 04 2007`
	EXTENSIONS	`More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 24 2007`

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Last modified November 27 22:38 EST 2009. Contains 167602 sequences.

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