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 1-2 of 2 results.

A079007 a(n) = smallest prime p_k such that the n successive differences between the primes p_k through p_(k+n) are all distinct.

Original entry on oeis.org

2, 2, 2, 17, 83, 113, 491, 1367, 1801, 5869, 15919, 34883, 70639, 70657, 214867, 214867, 2515871, 3952733, 13010143, 30220163, 60155567, 69931991, 203674907, 1092101119, 1363592621, 1363592677, 2124140323, 23024158649, 30282104173, 30282104173, 196948778371
Offset: 0

Views

Author

Labos Elemer, Jan 03 2002

Keywords

Examples

			a(0) = 2; a(1) = 2 from {2,3} with a single difference 1; a(2) = 2 from {2,3,5}, with two distinct differences 1, 2.
a(5) = p_30 = 113 because 113 is followed by 127, 131, 137, 139, 149, with 5 different differences: 14, 4, 6, 2, 10; and no smaller prime has this property.
		

Crossrefs

Cf. A001223, A068843, A053597, A078515. Different from A079889.

Programs

  • Mathematica
    f[k_, n_] := Block[{p = Table[ Prime[i], {i, k, k + n - 1}]}, Length[ Union[Drop[p, 1] - Drop[p, -1]]]]; k = 1; Do[ While[ f[k, n] != n - 1, k++ ]; Print[ Prime[k]], {n, 1, 22}]

Extensions

Edited by Robert G. Wilson v and N. J. A. Sloane, Jan 05 2002
More terms from Don Reble, Jan 15 2003
a(27)-a(30) from Donovan Johnson, Oct 23 2012

A078515 Numbers n such that A053597(n) sets a new record.

Original entry on oeis.org

1, 7, 23, 30, 94, 219, 279, 773, 1856, 3724, 6999, 7000, 19205, 184163, 280103, 849876, 1870722, 3570761, 4114341, 11271072, 55282774, 68256040, 68256041, 104011359, 1009322491, 1311699253, 7889803997
Offset: 1

Views

Author

N. J. A. Sloane, Jan 07 2003

Keywords

Crossrefs

Gives RECORDS transform of A053597. The corresponding primes are in A079889. See also A079007.

Programs

  • Mathematica
    f[n_] := Block[{k = 1}, While[p = Table[ Prime[i], {i, n, n + k}]; Length[ Union[Drop[p, 1] - Drop[p, -1]]] == k, k++ ]; k - 1]; a = Table[0, {50}]; Do[b = f[n]; If[ a[[b]] == 0, a[[b]] = n], {n, 1, 19000000}]

Extensions

More terms from Robert G. Wilson v and Klaus Brockhaus, Jan 08 2003
a(21)-a(27) from Donovan Johnson, Oct 23 2012
Showing 1-2 of 2 results.