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A176544 Primes of the form semiprime(k)/sum of digits of semiprime(k). 0
7, 37, 19, 67, 19, 19, 37, 37, 73, 37, 73, 337, 367, 163, 73, 109, 127, 73, 109, 163, 127, 181, 163, 433, 181, 163, 199, 181, 271, 163, 199, 199, 271, 271, 397, 307, 307, 487, 379, 541, 433, 577, 397, 271, 631, 433, 379, 487, 919, 1459, 541, 937, 811, 631, 991 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..55.

FORMULA

a(n) = p = A001358(n)/A175013(n).

a(n) = A001358(A176543(n))/A175013(A176543(n)). - R. J. Mathar, Apr 26 2010

EXAMPLE

7 is a term because 7 = 21/(2+1);

37 is a term because 37 = 111/(1+1+1).

MAPLE

A175013 := proc(n) A007953(A001358(n)) ; end proc: A007953 := proc(n) add(d, d=convert(n, base, 10)) ; end proc: for n from 1 to 4000 do r := A001358(n)/A175013(n) ; if type(r, 'integer') then if isprime(r) then printf("%d, ", r) ; end if; end if; end do: # R. J. Mathar, Apr 26 2010

CROSSREFS

Cf. A001358 (semiprimes), A007953 (sum of digits), A175013, A176543.

Sequence in context: A120106 A240274 A129737 * A281994 A246603 A043374

Adjacent sequences:  A176541 A176542 A176543 * A176545 A176546 A176547

KEYWORD

nonn,base

AUTHOR

Juri-Stepan Gerasimov, Apr 20 2010

EXTENSIONS

More terms from R. J. Mathar, Apr 26 2010

STATUS

approved

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Last modified December 5 17:42 EST 2019. Contains 329768 sequences. (Running on oeis4.)