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Triangular and Heptagonal Hindrance (Posted on 2022-12-22) Difficulty: 3 of 5
Each of x and y is a positive integer that satisfies this equation:
xoC=yoF

Determine the minimum value of x+y such that:
x is a triangular number and, y is a heptagonal pyramidal number.
What is the next smallest value of x+y?

*** oF = (9/5)*oC+32, where oF represents degree Fahrenheit and, oC represents degree Celsius.

See The Solution Submitted by K Sengupta    
Rating: 5.0000 (1 votes)

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Some Thoughts Not a Cannonball Comment 3 of 3 |
There is a classic problem called the "Cannonball Problem".  We have a version of that problem with "S.o.S is S".  The relevance to this problem is that both problems can be reduced to finding integer points (x,y) on a curve of the form y^2 = ax^3 + bx^2 + cx + d, which is a form of an elliptic curve!

In "S.o.S is S", I noted that it has been proven that there exactly two solutions to that problem, and I suspect we have the same sort of thing here.  That is to say the two solutions, (x,y) equals (630, 1166) or (820, 1508), found by Charlie and Larry are in fact ALL the positive integer solutions.

  Posted by Brian Smith on 2022-12-22 14:45:34
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