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A103710 Decimal expansion of the ratio of the latus rectum arc of any parabola to its semi latus rectum. +0
6
2, 2, 9, 5, 5, 8, 7, 1, 4, 9, 3, 9, 2, 6, 3, 8, 0, 7, 4, 0, 3, 4, 2, 9, 8, 0, 4, 9, 1, 8, 9, 4, 9, 0, 3, 8, 7, 5, 9, 7, 8, 3, 2, 2, 0, 3, 6, 3, 8, 5, 8, 3, 4, 8, 3, 9, 2, 9, 9, 7, 5, 3, 4, 6, 6, 4, 4, 1, 0, 9, 6, 6, 2, 6, 8, 4, 1, 3, 3, 1, 2, 6, 6, 8, 4, 0, 9, 4, 4, 2, 6, 2, 3, 7, 8, 9, 7, 6, 1, 5, 5, 9, 1, 7, 5 (list; cons; graph; listen)
OFFSET

1,1

COMMENT

All parabolas are similar (Ogilvy, 1969). Just as the ratio of a semicircle to its radius is always pi, the ratio of the latus rectum arc of any parabola to its semi latus rectum is sqrt(2) + ln(1 + sqrt(2)).

The Universal Parabolic Constant, equal to the ratio of the latus rectum arc of any parabola to its focal parameter. Like pi, it is transcendental.

REFERENCES

C. E. Love, Differential and Integral Calculus, 4th ed., Macmillan, 1950, pp. 286-288.

C. S. Ogilvy, Excursions in Geometry, Oxford Univ. Press, 1969, p. 84.

S. Reese, A universal parabolic constant, 2004, preprint.

LINKS

S. R. Finch, Mathematical Constants, addenda, section 8.1

Eric Weisstein's World of Mathematics, Universal Parabolic Constant

Eric Weisstein et al., Universal Parabolic Constant

FORMULA

sqrt(2) + ln(1 + sqrt(2)).

EXAMPLE

2.29558714939263807403429804918949038759783220363858348392997534664...

MATHEMATICA

RealDigits[ Sqrt[2] + Log[1 + Sqrt[2]], 10, 111][[1]] (from Robert G. Wilson v Feb 14 2005)

CROSSREFS

Cf. A002193 + A091648.

See also A103711, A103712.

Sequence in context: A157216 A020776 A021002 this_sequence A093589 A073315 A066320

Adjacent sequences: A103707 A103708 A103709 this_sequence A103711 A103712 A103713

KEYWORD

cons,easy,nonn

AUTHOR

Sylvester Reese and Jonathan Sondow (jsondow(AT)alumni.princeton.edu), Feb 13 2005

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Last modified November 22 20:51 EST 2009. Contains 167312 sequences.


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