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A143813 Sum of two powerful numbers greater than 1. 1
8, 12, 13, 16, 17, 18, 20, 24, 25, 29, 31, 32, 33, 34, 35, 36, 40, 41, 43, 44, 45, 48, 50, 52, 53, 54, 57, 58, 59, 61, 63, 64, 65, 68, 72, 73, 74, 76, 80, 81, 85, 88, 89, 90, 91, 96, 97, 98, 99, 100, 104, 106, 108, 109, 112, 113, 116, 117, 121, 124, 125, 127 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A076871 is the primary sequence.

LINKS

Table of n, a(n) for n=1..62.

EXAMPLE

8 = 4 + 4, 12 = 4 + 8, 13 = 4 + 9.

PROG

(PARI) isP(n)={

  n>3 && vecmin(factor(n)[, 2])>1

};

sumset(a, b)={

  my(c=vector(#a*#b));

  for(i=1, #a,

    for(j=1, #b,

      c[(i-1)*#b+j]=a[i]+b[j]

    )

  );

  vecsort(c, , 8)

};

upto(lim)={

  my(v=select(isP, vector(floor(lim), i, i)));

  select(n->n<=lim, sumset(v, v))

};

CROSSREFS

Sequence in context: A325809 A173461 A295782 * A290135 A225533 A143845

Adjacent sequences:  A143810 A143811 A143812 * A143814 A143815 A143816

KEYWORD

nonn

AUTHOR

Charles R Greathouse IV, Jul 06 2011

STATUS

approved

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Last modified June 19 19:11 EDT 2019. Contains 324222 sequences. (Running on oeis4.)