|
| |
|
|
A037175
|
|
Numbers n such that |s(n)-n| = number of primes <= n, where s(n) is sigma(n)-n.
|
|
0
| |
|
|
2, 3, 15, 22, 98, 460, 5408, 21170, 243568, 3587402, 25881424, 25888784, 33305870, 61202192, 115333190, 135135182, 167241932, 788355824, 788360176, 1653570248
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
COMMENTS
| a(21) > 10^11. - Donovan Johnson, Aug 15 2011
|
|
|
MAPLE
| with(numtheory):np:=0: for n from 1 to 300000 do if isprime(n) then np:=np+1 fi: if(abs(sigma(n)-2*n)=np) then printf("%d, ", n) fi od: (C. Ronaldo)
|
|
|
PROG
| (PARI) np=0; for(n=1, 10000000, if(isprime(n), np=np+1); if(abs(sigma(n)-2*n)==np, print1(n, ", "))) (Ronaldo)
|
|
|
CROSSREFS
| Sequence in context: A173334 A101507 A047176 * A048613 A162890 A030072
Adjacent sequences: A037172 A037173 A037174 * A037176 A037177 A037178
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Naohiro Nomoto (6284968128(AT)geocities.co.jp)
|
|
|
EXTENSIONS
| More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Dec 30 2004
a(11)-a(20) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Aug 15 2011
|
| |
|
|
