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 1-4 of 4 results.

A032605 Prime numbers indexed by lucky numbers.

Original entry on oeis.org

2, 5, 17, 23, 41, 47, 73, 97, 127, 137, 157, 191, 227, 233, 307, 331, 347, 367, 379, 401, 449, 487, 523, 571, 607, 631, 709, 727, 751, 761, 811, 877, 937, 967, 1009, 1019, 1129, 1171, 1187, 1229, 1259, 1297, 1367, 1409, 1453, 1483, 1489, 1523
Offset: 1

Views

Author

Patrick De Geest, May 15 1998

Keywords

Crossrefs

Programs

Formula

a(n) = A000040(A000959(n)). - Amiram Eldar, Nov 16 2019

A307009 Numbers that are both lucky-indexed primes and prime-indexed lucky numbers.

Original entry on oeis.org

367, 487, 3499, 5503, 11677, 15187, 15661, 20359, 27091, 31723, 36529, 43669, 60631, 62047, 70783, 72493, 74101, 78487, 93139, 94789, 105529, 123619, 128257, 148249, 164377, 191491, 192931, 210739, 240379, 242413, 271501, 276343, 282589, 290119, 299107
Offset: 1

Views

Author

Amiram Eldar, Mar 19 2019

Keywords

Comments

Intersection of A032605 and A032606.

Crossrefs

Programs

  • Mathematica
    m = 10^4; L = Table[2*i + 1, {i, 0, m}]; For[n = 2, n < Length[L], r = L[[n++]]; L = ReplacePart[L, Table[r*i -> Nothing, {i, 1, Length[L]/r}]]]; P = Select[ Range[2m], PrimeQ]; lp = L[[Select[P, # <= Length[L] &]]]; pl = P[[Select[L, # <= Length[P] &]]]; Intersection[lp, pl] (* after Jean-François Alcover at A000959 *)

A307010 Numbers that are prime-indexed primes, lucky-indexed lucky numbers, lucky-indexed primes and prime-indexed lucky numbers.

Original entry on oeis.org

367, 687331, 1983913, 2278033, 2400793, 2760361, 3531247, 5840767, 9429223, 11894593, 13201483, 13371751, 13597357, 13755361, 19782127, 24772663, 25607341, 34723783, 51279127, 56208967, 59215327, 71039257, 74498731, 83170537, 97983187, 109510909, 124762969
Offset: 1

Views

Author

Amiram Eldar, Mar 19 2019

Keywords

Comments

Intersection of A006450, A032639, A032605 and A032606.
Intersection of A307008 and A307009.

Crossrefs

Programs

  • Mathematica
    m = 10^4; L = Table[2*i + 1, {i, 0, m}]; For[n = 2, n < Length[L], r = L[[n++]]; L = ReplacePart[L, Table[r*i -> Nothing, {i, 1, Length[L]/r}]]]; P = Select[ Range[2m], PrimeQ]; lp = L[[Select[P, # <= Length[L] &]]]; pl = P[[Select[L, # <= Length[P] &]]]; pp = P[[Select[P, # <= Length[P] &]]]; ll = L[[Select[L, # <= Length[L] &]]]; Intersection[lp, pl, pp, ll] (* after Jean-François Alcover at A000959 *)

A128886 a(n) = prime(lucky(n)) - lucky(prime(n)).

Original entry on oeis.org

-1, -2, 4, 2, 4, -2, 4, 22, 28, 4, 16, 2, 22, 14, 70, 48, 28, 40, 12, 2, 34, 24, 36, 42, 24, 16, 88, 82, 96, 68, 10, 46, 52, 70, 30, 28, 106, 84, 82, 62, 56, 78, 82, 106, 114, 118, 18, -40, 52, 66, 68, 52, 136, 70, 46, 52, 54, 64, 112, 78, 114, 94, 10, 50, 82, 82, 4, 136, 90, 74
Offset: 1

Views

Author

Jonathan Vos Post, May 08 2007

Keywords

Comments

Commutator [prime,lucky] = [A032605, A032606].

Examples

			a(1) = Prime(Lucky(1)) - Lucky(Prime(1)) = Prime(1) - Lucky(2) = 2 - 3 = -1.
a(2) = Prime(Lucky(2)) - Lucky(Prime(2)) = Prime(3) - Lucky(3) = 5 - 7 = -2.
a(3) = Prime(Lucky(3)) - Lucky(Prime(3)) = Prime(7) - Lucky(5) = 17 - 13 = 4.
		

Crossrefs

Cf. A000040, A000959, A032605 (Prime numbers indexed by lucky numbers), A032606 (Lucky numbers indexed by prime numbers).

Programs

Formula

a(n) = A000040(A000959(n)) - A000959(A000040(n)).

Extensions

Entries corrected starting at a(10) by R. J. Mathar, Oct 22 2010
Showing 1-4 of 4 results.