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A076387 Numbers n such that sum of digits in base 9 is a divisor of sum of prime divisors (A008472). 8
2, 3, 5, 7, 9, 21, 27, 65, 69, 70, 81, 84, 90, 110, 123, 126, 130, 133, 154, 189, 222, 228, 243, 252, 259, 264, 327, 329, 333, 340, 342, 343, 350, 365, 372, 381, 402, 434, 450, 516, 528, 580, 588, 618, 621, 650, 684, 729, 730, 731, 738, 740, 741, 756, 765, 774 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The sequence is infinite because, for m = 9^k, k >= 0, digsum(m_9) = 1. - Marius A. Burtea, Jul 10 2019

LINKS

Marius A. Burtea, Table of n, a(n) for n = 1..5189

EXAMPLE

21 = 23_9, digsum(23_9) = 5, PrimeDivisors(21) = {3, 7}, sopf(21) = 3+7 = 10 = 5*2.

MAPLE

A076387 := proc(n) local i, j, t, t1, sod, sopd; t := NULL; for i from 2 to n do t1 := i; sod := 0; while t1 <> 0 do sod := sod + (t1 mod 9); t1 := floor(t1/9); od; sopd := 0; j := 1; while ithprime(j) <= i do if i mod ithprime(j) = 0 then sopd := sopd+ithprime(j); fi; j := j+1; od; if sopd mod sod = 0 then t := t, i; fi; od; t; end;

PROG

(PARI) {for(ixp=2, 783,

casi=ixp; cvst=0; dsu=0; M=factor(ixp); smt=0;

for(i=1, matsize(M)[1], smt=smt+M[i, 1]);

while(casi!=0,

cvd=casi%9; dsu=dsu+cvd; casi=(casi-cvd)/9);

if(smt%dsu==0, print1(ixp, ", ")))} \\ Douglas Latimer, May 08 2012

(Magma) [n: n in [1..800]| &+PrimeDivisors(n) mod &+Intseq(n, 9) eq 0] ; // Marius A. Burtea, Jul 10 2019

CROSSREFS

Cf. A075657, A076380 - A076387.

Sequence in context: A036959 A108031 A280429 * A193622 A265249 A214331

Adjacent sequences: A076384 A076385 A076386 * A076388 A076389 A076390

KEYWORD

nonn,base

AUTHOR

Floor van Lamoen, Oct 08 2002

STATUS

approved

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Last modified December 2 17:51 EST 2022. Contains 358510 sequences. (Running on oeis4.)