A133968 Home primes whose homeliness is 7.

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

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