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A084071 Class 12+ primes. 9
68198461, 115084901, 138358573, 156811273, 213397621, 220576331, 234432217, 260050573, 282261961, 290996753, 330864497, 353653063, 371500819, 383616341, 406915273, 426240379, 445800983, 446707201, 449558323, 460339577, 472782553 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

R. K. Guy, Unsolved Problems in Number Theory, A18.

LINKS

Table of n, a(n) for n=1..21.

MAPLE

For Maple program see Mathar link in A005105.

MATHEMATICA

PrimeFactors[n_Integer] := Flatten[ Table[ #[[1]], {1}] & /@ FactorInteger[n]]; f[n_Integer] := Block[{m = n}, If[m == 0, m = 1, While[ IntegerQ[m/2], m /= 2]; While[ IntegerQ[m/3], m /= 3]]; Apply[Times, PrimeFactors[m] + 1]]; ClassPlusNbr[n_] := Length[ NestWhileList[f, n, UnsameQ, All]] - 3; Prime[ Select[ Range[25000000], ClassPlusNbr[ Prime[ # ]] == 12 &]]

CROSSREFS

Cf. A005113, A005105, A005106, A005107, A005108, A081633, A081634, A081635, A081636, A081637, A081638, A081639.

Sequence in context: A256274 A158890 A230746 * A251615 A321706 A172608

Adjacent sequences:  A084068 A084069 A084070 * A084072 A084073 A084074

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Mar 20 2003

STATUS

approved

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Last modified April 18 06:48 EDT 2019. Contains 322209 sequences. (Running on oeis4.)