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.

A152757 Numbers k such that the deficiency of k plus the number of proper divisors of k is a prime number (see A152864).

Original entry on oeis.org

2, 3, 4, 5, 6, 7, 9, 10, 11, 13, 14, 16, 17, 18, 19, 20, 21, 22, 23, 26, 27, 28, 29, 31, 34, 37, 38, 41, 43, 45, 46, 47, 49, 52, 53, 55, 57, 58, 59, 61, 62, 64, 67, 70, 71, 73, 74, 75, 76, 77, 79, 82, 83, 86, 88, 89, 91, 93, 94, 95, 97, 99, 101, 103, 104, 106, 107, 109, 110, 111
Offset: 1

Views

Author

Omar E. Pol, Dec 14 2008

Keywords

Links

Crossrefs

Cf. A000005, A000203, A033879, A032741, A152770, A152864.

Programs

  • Maple
    with(numtheory): a := proc (n) if isprime(2*n-sigma(n)+tau(n)-1) = true then n else end if end proc: seq(a(n), n = 1 .. 120); # Emeric Deutsch, Jan 08 2009

Extensions

Extended by Emeric Deutsch, Jan 08 2009
Name edited by Jon E. Schoenfield, Jan 06 2019

A152758 Numbers k such that the deficiency of k plus the number of proper divisors of k is not a prime number (see A152864).

Original entry on oeis.org

1, 8, 12, 15, 24, 25, 30, 32, 33, 35, 36, 39, 40, 42, 44, 48, 50, 51, 54, 56, 60, 63, 65, 66, 68, 69, 72, 78, 80, 81, 84, 85, 87, 90, 92, 96, 98, 100, 102, 105, 108, 112, 114, 116, 117, 120, 121, 123, 126, 128, 129, 130, 132, 136, 138, 140, 141, 143, 144, 148, 150, 153
Offset: 1

Views

Author

Omar E. Pol, Dec 14 2008

Keywords

Crossrefs

Cf. A000005, A000040, A000203, A032741, A033879, A152757, A152770, A152864.

Programs

  • Maple
    with(numtheory): a := proc (n) if isprime(2*n-sigma(n)+tau(n)-1) = false then n else end if end proc: seq(a(n), n = 1 .. 200); # Emeric Deutsch, Jan 08 2009

Extensions

Extended by Emeric Deutsch, Jan 08 2009
Name edited by Jon E. Schoenfield, Jan 06 2019

A152984 Absolute values of A152864.

Original entry on oeis.org

1, 2, 3, 3, 5, 3, 7, 4, 7, 5, 11, 1, 13, 7, 9, 5, 17, 2, 19, 3, 13, 11, 23, 5, 21, 13, 17, 5, 29, 5, 31, 6, 21, 17, 25, 11, 37, 19, 25, 3, 41, 5, 43, 9, 17, 23, 47, 19, 43, 12, 33, 11, 53, 5, 41, 1, 37, 29, 59, 37, 61, 31, 27, 7, 49, 5, 67, 15, 45, 3, 71, 40, 73, 37, 31, 17, 61, 5, 79, 17
Offset: 1

Views

Author

Omar E. Pol, Dec 19 2008

Keywords

Crossrefs

Cf. A152864.

Programs

  • Maple
    A152864 := proc(n) 2*n-numtheory[sigma](n)+numtheory[tau](n)-1 ; end: A152984 := proc(n) abs(A152864(n)) ; end: for n from 1 to 120 do printf("%d,",A152984(n)) ; od: # R. J. Mathar, Jan 22 2009

Extensions

Few more terms from R. J. Mathar, Jan 22 2009
Showing 1-3 of 3 results.

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