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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

User: Shashi Kant Pandey

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Shashi Kant Pandey has authored 1 sequences.

A345894 Positive integers representable by the two cyclotomic binary forms Phi_5(x,y) and Phi_12(u,v).

Original entry on oeis.org

1, 16, 61, 81, 256, 625, 976, 1296, 2401, 4096, 4941, 6561, 10000, 14641, 15616, 20736, 28561, 38125, 38416, 50625, 65536, 79056, 83521, 104976, 130321, 146461, 160000, 194041, 194481, 229981, 234256, 249856, 279841, 331776, 390625, 400221, 456976, 531441
Offset: 1

Author

Shashi Kant Pandey, Jul 23 2021

Keywords

Comments

Positive integers C such that Phi_5(x,y) = Phi_12(u,v) = C has a solution with nonzero (x,y,u,v).
A cyclotomic binary form over Z is a homogeneous polynomial in two variables which has the form f(x, y) = y^EulerPhi(k)*CyclotomicPolynomial(k, x/y) where k is some integer >= 3. An integer n is represented by f if f(x,y) = n has an integer solution.

Examples

			Phi_5(1,-3) = 1^4 + 1^3*(-3) + 1^2*(-3)^2 + 1*(-3)^3 + (-3)^4 = 1 - 3 + 9 - 27 + 81 = 61 and Phi_12(2, 3) = 2^4 - 2^2*3^2 + 3^4 = 16 - 36 + 81 = 61, so 61 is a term.
		

Crossrefs

Cf. A296095.

Extensions

a(8)-a(38) from Jon E. Schoenfield, Jul 24 2021