A133964 Home primes whose homeliness is 5.

773, 1129, 3137, 3251, 3593, 3797, 7541, 7853, 23167, 23557, 23719, 23743, 23773, 23971, 31973, 33191, 33331, 33769, 33863, 37307, 37573, 37691, 37997, 39733, 39929, 47797, 53101, 61613, 67349, 67709, 71129, 71171, 71443, 71719, 73181

Offset

1,1

Comments

Number of terms < 10^n: 0, 0, 1, 8, 44, 417, 3299, ... .

Links

Table of n, a(n) for n=1..35.

Example

Only (10, 25, 55, 511, 773) -> 773, etc.

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 = 5 - 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, 45]

Crossrefs

Cf. A037274, A118756, A133963, A133956, A133957, A133958, A133960, A133962, A133966, A133968, A133970, A133972, A133974, A133976, A133978.

Sequence in context: A264255 A240843 A133963 * A033919 A055521 A060825

Adjacent sequences: A133961 A133962 A133963 * A133965 A133966 A133967

Keyword

nonn,base

Author

Robert G. Wilson v, Sep 30 2007

Status

approved