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 1-5 of 5 results.

A069351 Primes having no representation of the form n + A001222(n), complement of A069348.

Original entry on oeis.org

2, 5, 7, 13, 19, 29, 43, 61, 83, 103, 107, 109, 137, 149, 197, 227, 263, 281, 283, 347, 349, 353, 389, 443, 457, 467, 479, 523, 541, 563, 569, 571, 587, 619, 643, 647, 653, 659, 677, 743, 761, 797, 811, 821, 827, 863, 883, 937
Offset: 1

Views

Author

Reinhard Zumkeller, Mar 18 2002

Keywords

Crossrefs

Cf. A069350.

Programs

  • PARI
    is(n)=for(k=1,log(n+.5)\log(2),if(bigomega(n-k)==k, return(0))); isprime(n) \\ Charles R Greathouse IV, Dec 10 2013

A069349 Number of ways to represent primes as A069348(n)=k+A001222(k).

Original entry on oeis.org

1, 2, 1, 2, 1, 2, 1, 1, 3, 1, 1, 2, 1, 2, 1, 1, 1, 3, 1, 1, 1, 1, 2, 1, 2, 2, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 3, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 3, 2, 2, 2, 1, 2, 1, 1, 1, 1, 3, 1, 1, 1, 2, 1, 2, 1, 1, 3, 1, 1, 1, 3, 3, 1, 1, 2, 1, 2, 1, 2, 2, 1, 1, 2, 1, 2, 2
Offset: 1

Views

Author

Reinhard Zumkeller, Mar 18 2002

Keywords

Examples

			a(9)=3 as: A069348(9)=53=A064800(48)=A064800(50)=A064800(51)
53=2*2*2*2*3+5 and 53=2*5*5+3 and 51=3*17+2.
		

A069346 Primes of the form n - Omega(n), where Omega(n) is the number of prime factors of n, A001222(n).

Original entry on oeis.org

2, 5, 7, 13, 17, 19, 23, 31, 37, 41, 43, 47, 53, 67, 73, 83, 89, 103, 107, 109, 113, 127, 131, 139, 151, 157, 163, 167, 179, 181, 199, 211, 227, 233, 239, 241, 251, 257, 263, 281, 283, 293, 307, 311, 313, 317, 337, 347, 353, 359
Offset: 1

Views

Author

Reinhard Zumkeller, Mar 18 2002

Keywords

Comments

The representation is ambiguous, see A069347.

Examples

			a(10) = 41 = A069345(44) = 44-3 (as 44 = 2*2*11).
		

Crossrefs

Programs

  • Mathematica
    Select[Table[n - PrimeOmega[n], {n, 1, 400}], PrimeQ] // Union (* Jean-François Alcover, Jun 08 2013 *)
  • PARI
    is(n)=for(k=1, log(n)\log(2)+1, if(bigomega(n+k)==k, return(isprime(n)))); 0 \\ Charles R Greathouse IV, Dec 10 2013

A069358 Primes of the form 2^i*3^j + (i+j) with i, j >= 0.

Original entry on oeis.org

3, 11, 37, 53, 113, 167, 199, 439, 521, 3083, 6569, 12301, 23339, 32783, 139981, 663569, 708601, 3981331, 7558289, 20155411, 38263769, 45349651, 75497497, 483729431, 1934917657, 2717909021, 6115295261, 12397455671, 14693280793
Offset: 1

Views

Author

Reinhard Zumkeller, Mar 18 2002

Keywords

Crossrefs

Programs

  • Mathematica
    Take[ Select[ Union[ Flatten[ Table[2^i*3^j + (i + j), {i, 0, 25}, {j, 0, 18}]]], PrimeQ[ # ] &], 30]

Extensions

Edited and extended by Robert G. Wilson v, May 09 2003

A173032 Primes having no representation of the form n -+ Omega(n), where Omega is A001222.

Original entry on oeis.org

29, 61, 137, 149, 197, 349, 457, 523, 569, 619, 659, 1091, 1153, 1303, 1483, 1549, 1723, 1861, 1873, 2339, 2347, 2377, 2593, 2753, 2851, 3121, 3169, 3257, 3323, 3391, 3469, 3539, 4051, 4177, 4373, 4423, 4483, 4547, 4691, 4799, 4877, 4933, 4943, 5101, 5237
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Nov 21 2010

Keywords

Comments

Intersection of A069350 and A069351.

Crossrefs

Programs

  • PARI
    is(n)=for(k=1, log(n)\log(2)+1, if(bigomega(n+k)==k||bigomega(n-k)==k, return(0))); isprime(n) \\ Charles R Greathouse IV, Dec 10 2013
Showing 1-5 of 5 results.