cp's OEIS Frontend

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.

Showing 1-3 of 3 results.

A288144 Square roots of the deficiencies of the squares of A289274.

Original entry on oeis.org

19, 53, 1583, 3509, 6479, 223309, 291205, 65791, 56179, 50039, 3505843, 456456275, 16781311, 5734169, 4144461731, 23461111, 56585278013, 50656373, 164136392937
Offset: 1

Views

Author

Jens Voß, Jul 01 2017

Keywords

Comments

This sequence consists of the terms of A288145 different from 1.

Examples

			The deficiency of 46^2 is 2*46^2 - sigma(46^2) = 19^2, so this sequence starts with 19 (since 46 is the first term of the A289274).

Crossrefs

Cf. A289274, A289275, A288145.

Extensions

a(10) from Chai Wah Wu, Jul 26 2017
a(11)-a(19) from Giovanni Resta, Jul 27 2017

A289275 Numbers k such that the deficiency of k^2 is itself a square.

Original entry on oeis.org

1, 2, 4, 8, 16, 32, 46, 64, 128, 256, 284, 512, 1024, 1633, 2048, 4096, 8192, 16384, 32768, 65536, 131072, 149728, 242656, 260495, 262144, 298057, 524288, 1048576, 1056752, 2097152, 4194304, 8388608, 9587584, 16777216, 17706256, 33554432, 67108864, 134217728
Offset: 1

Views

Author

Jens Voß, Jun 30 2017

Keywords

Comments

The sequence of square roots of the deficiencies of this sequence is A288145.
The current sequence is the disjoint union of the powers of 2 (A000079) and the sequence A289274.

Links

Crossrefs

Disjoint union of the sequences A000079 and A289274.
Square roots of deficiencies of squares is A288145.

Programs

  • Mathematica
    Select[Range[10^5], IntegerQ@ Sqrt[2 #^2 - DivisorSigma[1, #^2]] &] (* Michael De Vlieger, Jul 04 2017 *)
  • PARI
    isok(n) = issquare(2*n^2 - sigma(n^2)); \\ Michel Marcus, Jul 01 2017

Extensions

a(35)-a(38) from Giovanni Resta, Jul 27 2017

A288145 Square roots of the deficiencies of the squares of A289275.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 19, 1, 1, 1, 53, 1, 1, 1583, 1, 1, 1, 1, 1, 1, 1, 3509, 6479, 223309, 1, 291205, 1, 1, 65791, 1, 1, 1, 56179, 1, 50039, 1, 1, 1, 1, 1, 3505843, 456456275, 1, 16781311, 5734169, 1, 4144461731, 1, 1, 23461111, 1, 1, 1, 56585278013
Offset: 1

Views

Author

Jens Voß, Jul 01 2017

Keywords

Comments

The terms different from 1 in this sequence form sequence A288144.

Links

Crossrefs

Cf. A289275, A288144, A289274.

Extensions

a(35)-a(54) from Giovanni Resta, Jul 27 2017
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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