A196527 -id:A196527 - cp's OEIS frontend

A196528 Smallest number m such that A196527(m) = n.

4, 1, 26, 11, 2, 57, 13, 15, 179, 77, 382, 161, 92, 635, 376, 513, 222, 331, 420, 1961, 4080, 933, 685, 103, 386, 49, 1233, 33, 3520, 1317, 196, 1301, 562, 3765, 902, 1769, 7549, 547, 1938, 3349, 1124, 3345, 545, 275, 6606, 21277, 88, 3247, 1411, 955, 6921

Offset: 1

Reinhard Zumkeller, Oct 03 2011

nonn

Smallest number m such that n equals the greatest common divisor of sums of first n prime numbers and first n composite numbers:

A196527(a(n)) = n and A196527(m) <> n for m < a(n).

Reinhard Zumkeller, Table of n, a(n) for n = 1..100

A196529 Half of greatest common divisor of products of first n prime numbers and first n composite numbers.

Original entry on oeis.org

1, 3, 3, 3, 15, 15, 105, 105, 105, 105, 105, 105, 1155, 1155, 1155, 15015, 15015, 15015, 15015, 15015, 15015, 255255, 255255, 255255, 4849845, 4849845, 4849845, 4849845, 4849845, 4849845, 111546435, 111546435, 111546435, 111546435, 111546435, 111546435

Offset: 1

Reinhard Zumkeller, Oct 03 2011

nonn

a(n) = gcd(A002110(n),A036691(n)) / 2.

			a(3) = gcd(2*3*5,4*6*8)/2 = gcd(30,192)/2 = 6/2 = 3;
a(4) = gcd(2*3*5*7,4*6*8*9)/2 = gcd(210,1728)/2 = 6/2 = 3;
a(5) = gcd(2*3*5*7*11,4*6*8*9*10)/2 = gcd(2310,17280)/2 = 30/2 = 15.

Reinhard Zumkeller, Table of n, a(n) for n = 1..1000

Cf. A196527, A070826.

nn=40;With[{prs=Prime[Range[nn]],comps=Take[Complement[Range[Prime[nn]], Prime[ Range[nn]]],nn]},Rest[Table[GCD[Times@@Take[prs,n], Times@@Take[ comps,n]]/2,{n,nn}]]] (* Harvey P. Dale, Oct 16 2011 *)

cp's OEIS Frontend

A196528 Smallest number m such that A196527(m) = n.

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A196529 Half of greatest common divisor of products of first n prime numbers and first n composite numbers.

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