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A055009 Smallest composite number x such that sigma(x + prime(n)#) = sigma(x) + prime(n)#, where prime(n)# = A002110(n) and sigma is A000203. 3
434, 104, 44, 176, 2924, 34256, 83509, 539081, 254963216, 14600541172, 201346999808 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(12) <= 14841476269604. a(13) <= 314064788156864. - Donovan Johnson, Mar 17 2013

LINKS

Table of n, a(n) for n=1..11.

EXAMPLE

a(7) = 83509 = 37*37*61, sigma(83509)+510510 = 87234+510510 = sigma(83509+510510) = sigma(594019) = 597744.

PROG

(PARI) a(n)=my(P=prod(i=1, n, prime(i)), x=4); while(isprime(x) || sigma(x+P) != sigma(x)+P, x++); x \\ Charles R Greathouse IV, Feb 14 2013

CROSSREFS

The prime solutions for particular sigma(x+primorial) = sigma(x)+primorial equations are in A049481-A049485.

A000203, A002110, A015913-A015917, A049902-A049905, A049481-A049485.

Sequence in context: A198450 A241925 A108832 * A054982 A108785 A219033

Adjacent sequences:  A055006 A055007 A055008 * A055010 A055011 A055012

KEYWORD

more,nonn

AUTHOR

Labos Elemer, May 31 2000

EXTENSIONS

a(9)-a(10) from Donovan Johnson, Oct 15 2008

a(11) from Donovan Johnson, Mar 08 2013

STATUS

approved

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Last modified November 15 11:14 EST 2019. Contains 329144 sequences. (Running on oeis4.)