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A064907 Semiprimes p1*p2 such that p2 mod p1 = 9. 1
341, 583, 731, 793, 893, 1067, 1469, 1793, 1807, 1943, 2201, 2323, 2483, 2519, 2761, 3043, 3071, 3487, 3497, 3781, 4213, 4439, 4511, 4777, 4841, 4849, 4939, 5497, 5809, 5933, 5947, 6511, 6539, 6989, 7093, 7117, 7391, 7493, 7601, 7613, 7783, 7891, 7967 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

John Cerkan, Table of n, a(n) for n = 1..10000

MATHEMATICA

spQ[n_]:=Module[{fi=FactorInteger[n][[All, 1]]}, PrimeOmega[n]==2&&Mod[ fi[[2]], fi[[1]]]==9]; Select[Range[8000], spQ]//Quiet (* Harvey P. Dale, Aug 02 2019 *)

PROG

(Python)

from sympy import factorint

def is_A064907(n):

    f = factorint(n)

    return (sum([f[i] for i in f]) == 2) and (max(f) % min(f) == 9)

def list_A064907(cnt):

    inx = 0

    n = 1

    an = []

    while inx < cnt:

        if is_A064907(n):

            an.append(n)

            inx += 1

        n += 2

    return an #John Cerkan, Apr 14 2018

(PARI) isok(n) = my(f = factor(n)); (#f~ == 2) && (vecmax(f[, 2]) < 2) && ((f[2, 1] % f[1, 1]) == 9); \\ Michel Marcus, Apr 16 2018

CROSSREFS

Cf. A001358 (p2 mod p1 = 0), A064899-A064911.

Sequence in context: A006970 A007324 A007011 * A043685 A043576 A215326

Adjacent sequences:  A064904 A064905 A064906 * A064908 A064909 A064910

KEYWORD

nonn

AUTHOR

Patrick De Geest, Oct 13 2001

EXTENSIONS

Offset changed by John Cerkan, Apr 12 2018

STATUS

approved

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Last modified August 17 17:25 EDT 2019. Contains 326059 sequences. (Running on oeis4.)