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A064155 Let p = x1x2x3...xk be a prime in base 10 with k digits. The sequence gives the primes p such that x1*x2*x3*...xk = k*(x1 + x2 + x3 + ... + xk). 2
2, 3, 5, 7, 167, 523, 617, 761, 1427, 2417, 2741, 4127, 4217, 4271, 4721, 126241, 126421, 146221, 212461, 216421, 221461, 224611, 226141, 241261, 242161, 246121, 261241, 262411, 264211, 421621, 426211, 621241, 642121, 642211, 1111457 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Harry J. Smith, Table of n, a(n) for n = 1..100

EXAMPLE

167 belongs to the sequence because 1*6*7 = 42 and 3*(1+6+7) = 42.

PROG

(PARI) ProdD(x)= { local(p); p=1; while (x>9 && p>0, p*=(x-10*(x\10)); x\=10); return(p*x) } SumD(x)= { local(s); s=0; while (x>9, s+=x-10*(x\10); x\=10); return(s + x) } digitsIn(x)= { local(d); if (x==0, return(1)); d=1 + log(x)\log(10); if (10^d == x, d++, if (10^(d-1) > x, d--)); return(d) } { n=r=0; for (m=1, 10^9, r=nextprime(r+1); if ((p=ProdD(r)) && p == digitsIn(r)*SumD(r), write("b064155.txt", n++, " ", r); if (n==100, break)) ) } \\ Harry J. Smith, Sep 09 2009

CROSSREFS

Sequence in context: A281021 A230046 A098463 * A230047 A230042 A230045

Adjacent sequences:  A064152 A064153 A064154 * A064156 A064157 A064158

KEYWORD

easy,nonn,base

AUTHOR

Felice Russo, Sep 14 2001

STATUS

approved

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Last modified November 28 07:52 EST 2021. Contains 349401 sequences. (Running on oeis4.)