login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A133968 Home primes whose homeliness is 7. 12
23251, 23761, 33797, 36389, 37643, 37951, 37967, 77711, 113779, 131777, 132749, 134129, 233347, 233617, 233881, 237547, 293863, 311677, 311821, 313619, 314627, 317743, 319547, 331319, 331907, 333139, 333271, 333457, 333791, 333911, 337517 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Number of terms < 10^n: 0, 0, 0, 0, 8, 80, 667, ... .

LINKS

Table of n, a(n) for n=1..31.

MATHEMATICA

lst = {}; f[n_] := FromDigits@ Flatten[ IntegerDigits@ Table[ #[[1]], {#[[2]]}] & /@ FactorInteger@n, 2]; h[n_] := NestWhileList[f@# &, n, !PrimeQ@# &, 1, 28]; Do[p = h[n][[ -1]]; If[ PrimeQ@p && p < 10^7 && p != n, Print[{n, p}]; AppendTo[lst, p]], {n, 2, 1000}];

d = 7 - 2; lsu = {}; Do[ If[ lst[[n]] == lst[[n + d]] && lst[[n - 1]] != lst[[n]] && lst[[n]] != lst[[n + d + 1]], AppendTo[lsu, lst[[n]]]], {n, 188004 - d - 1}]; Take[Union@ lsu, 35]

CROSSREFS

Cf. A037274, A118756, A133967, A133956, A133957, A133958, A133960, A133962, A133964, A133966, A133970, A133972, A133974, A133976, A133978.

Sequence in context: A126301 A205176 A205275 * A337784 A333746 A251111

Adjacent sequences: A133965 A133966 A133967 * A133969 A133970 A133971

KEYWORD

nonn,base

AUTHOR

Robert G. Wilson v, Sep 30 2007

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 26 04:58 EDT 2023. Contains 361529 sequences. (Running on oeis4.)