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A145781 Least m >= 0 which when added to primorial(n) yields a square. 3
2, 3, 6, 15, 91, 246, 715, 3535, 21099, 95995, 175470, 4468006, 31516774, 192339970, 212951314, 5138843466, 76699112491, 103728576730, 3051100701874, 14417674958635, 245230361204214, 2296196521511806, 10940476546738414 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
C. Aebi and G. Cairns, Partitions of primes, Parabola 45, Issue 1 (2009); see the table on p. 5. - Jonathan Sondow, Jun 21 2012
FORMULA
a(n) = A216144(n)^2 - A002110(n). - Jonathan Sondow, Sep 02 2012
EXAMPLE
a(1)= 4 - 2 = 2, a(2)= 9 - 2*3 = 3, a(3)= 36 - 2*3*5 = 6, a(4)= 225 - 2*3*5*7 = 15, and a(5)= 2401 - 2*3*5*7*11 = 91.
MATHEMATICA
(IntegerPart[Sqrt[#]]+1)^2-#&/@Rest[FoldList[Times, 1, Prime[Range[30]]]] (* Harvey P. Dale, Jan 14 2011 *)
PROG
(PARI) j=[]; for (n=1, 30, j=concat(j, (ceil(sqrt(prod(i=1, n, prime(i))))^2 -prod(i=1, n, prime(i))))); j
CROSSREFS
Sequence in context: A007364 A305857 A014627 * A351880 A109162 A215659
KEYWORD
nonn
AUTHOR
EXTENSIONS
Definition shortened and clarified by Jonathan Sondow, Sep 02 2012
STATUS
approved

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Last modified September 30 20:58 EDT 2023. Contains 365796 sequences. (Running on oeis4.)