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.

Previous Showing 11-13 of 13 results.

A121820 Numbers m such that greatest prime divisor of (m-th prime + 1) is 3.

Original entry on oeis.org

1, 3, 5, 7, 9, 15, 16, 20, 28, 43, 76, 83, 118, 150, 164, 190, 377, 597, 801, 889, 1091, 1561, 1814, 2601, 3016, 6253, 7281, 13005, 15167, 25607, 27191, 37126, 39419, 41357, 62946, 78155, 83024, 184383, 702826, 1146234, 1203569, 1595690, 1871469
Offset: 1

Views

Author

Zak Seidov, Sep 09 2006

Keywords

Comments

Or, position of 3 in A023509 Greatest prime divisor of n-th prime + 1.

Crossrefs

Cf. A023509.

Programs

  • Mathematica
    Select[Range[990000],FactorInteger[Prime[ # ]+1][[ -1,1]]==3&]

Extensions

More terms from Stefan Steinerberger, May 18 2007

A121846 Numbers m such that greatest prime divisor of (m-th prime + 1) is 5.

Original entry on oeis.org

8, 10, 17, 22, 24, 35, 41, 46, 52, 57, 72, 87, 92, 95, 109, 128, 140, 204, 207, 228, 239, 256, 303, 357, 393, 417, 430, 558, 646, 669, 685, 712, 950, 1117, 1198, 1315, 1389, 1454, 1526, 1543, 1600, 1794, 2140, 2289, 2312, 2425, 2571, 2851, 3368, 3613, 3824
Offset: 1

Views

Author

Zak Seidov, Sep 09 2006

Keywords

Comments

Or, position of 5 in A023509 Greatest prime divisor of n-th prime + 1.

Crossrefs

Cf. A023509.

Programs

  • Mathematica
    Reap[Do[If[FactorInteger[Prime[n]+1][[ -1,1]]==5,Sow[n]],{n,5000}]][[2,1]]

Formula

A023509(m)=5.

A174870 Odd indices m for which A174869(m) is <>1.

Original entry on oeis.org

1, 9, 21, 25, 27, 33, 45, 57, 75, 77, 81, 85, 91, 93, 105, 115, 117, 121, 125, 133, 135, 141, 145, 147, 165, 169, 171, 175, 177, 187, 189, 201, 205, 213, 217, 221, 225, 231, 235, 243, 245, 247, 253, 261, 273, 275, 289, 297, 301, 315, 325, 333, 343, 345, 355, 357, 361, 363
Offset: 1

Views

Author

Vladimir Shevelev, Mar 31 2010

Keywords

Comments

All but the first term in the sequence are composite numbers.

Examples

			The 9 refers to A174869(9) = 7. The 21 refers to A174869(21) = 3.

Crossrefs

Cf. A174869, A006530, A103667, A023503, A023509, A174857, A020639 ,A002618, A036689.

Extensions

More terms from R. J. Mathar, Aug 10 2010
Previous Showing 11-13 of 13 results.

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

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