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A077804 Deficient oblong numbers. 3
2, 110, 182, 506, 1406, 1892, 2162, 2756, 3422, 3782, 4556, 5402, 6806, 7310, 8930, 9506, 11342, 11990, 14042, 14762, 17030, 17822, 18632, 20306, 21170, 22052, 22952, 24806, 26732, 27722, 29756, 31862, 32942, 36290, 37442, 41006, 42230 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

"In 1700, Charles de Neuveglise claimed the product of two consecutive integers n(n+1) with n>=3 is abundant." -Tattersall, p. 133.

REFERENCES

Tattersall, J. "Elementary Number Theory in Nine Chapters", Cambridge University Press, 2001.

LINKS

Harvey P. Dale, Table of n, a(n) for n = 0..1000

MATHEMATICA

Select[Table[n(n+1), {n, 300}], DivisorSigma[1, #]<2#&] (* Harvey P. Dale, Oct 03 2011 *)

PROG

(PARI) for(n=1, 350, o=n*(n+1); if(sigma(o)<2*o, print1(o, ", ")))

CROSSREFS

Cf. A002378, A005101, A005100.

Sequence in context: A062656 A173372 A323250 * A063668 A006334 A093425

Adjacent sequences:  A077801 A077802 A077803 * A077805 A077806 A077807

KEYWORD

easy,nonn

AUTHOR

Jason Earls, Dec 03 2002

STATUS

approved

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Last modified May 15 16:02 EDT 2021. Contains 343920 sequences. (Running on oeis4.)