login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A103801 Indices n such that A019565(n)+/-2 are both primes. 0
4, 6, 10, 14, 22, 26, 34, 38, 62, 78, 106, 138, 142, 162, 190, 194, 230, 258, 274, 278, 302, 402, 430, 458, 494, 498, 534, 550, 618, 670, 674, 690, 694, 742, 770, 814, 822, 902, 934, 1014, 1030, 1038, 1062, 1090, 1102, 1106, 1142, 1146, 1182, 1222, 1234 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..51.

EXAMPLE

A019565(4)=5, 3 and 7 are both primes, so a(1)=4;

A019565(6)=15, 13 and 17 are both primes, so a(2)=6;

MATHEMATICA

A019565 = Function[tn, k1 = tn; o = 1; tt = 1; While[k1 > 0, k2 = Mod[k1, 2]; If[k2 == 1, tt = tt*Prime[o]]; k1 = (k1 - k2)/2; o = o + 1]; tt]; Do[cp1 = A019565[n] - 2; cp2 = cp1 + 4; If[PrimeQ[cp1] && PrimeQ[cp2], Print[n]], {n, 0, 20000}]

CROSSREFS

Cf. A019565, A103799, A103800.

Sequence in context: A091376 A100484 A076924 * A141247 A049632 A216732

Adjacent sequences:  A103798 A103799 A103800 * A103802 A103803 A103804

KEYWORD

easy,nonn

AUTHOR

Lei Zhou, Feb 22 2005

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 18 05:14 EST 2019. Contains 320245 sequences. (Running on oeis4.)