The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A260598 Numbers n such that the sum of the divisors of n equals the fourth power of the sum of the digits of n. 1
 1, 510, 11235, 12243, 14223, 136374, 142494, 145266, 148614, 163158, 171465, 181815, 214863, 240963, 246507, 323976, 397182, 404994, 1548798 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Let n be a k-digit number. Then, sigma(n) >= 10^(k-1) and (9*k)^4 >= sum_of_digits(n)^4. So, n must be less than 10^9. - Hiroaki Yamanouchi, Aug 29 2015 LINKS FORMULA A000583(A007953(a(n))) = A000203(a(n)). EXAMPLE 510 is in the sequence, since (1 + 2 + 3 + 5 + ... + 255 + 510) = (5 + 1 + 0)^4. MATHEMATICA n = 10000000; list = {}; x = 1; While[x <= n,   If[Total[Divisors[x]] == Total[IntegerDigits[x]]^4,    AppendTo[list, x]];   x = x + 1   ]; list PROG (PARI) isok(n) = sigma(n) == sumdigits(n)^4; \\ Michel Marcus, Aug 06 2015 (MAGMA) [n: n in [1..3*10^6] | DivisorSigma(1, n) eq (&+Intseq(n)^4)]; // Vincenzo Librandi, Aug 29 2015 CROSSREFS Cf. A000203, A000583, A007953, A055013. Sequence in context: A252882 A252883 A196674 * A255179 A144768 A196289 Adjacent sequences:  A260595 A260596 A260597 * A260599 A260600 A260601 KEYWORD nonn,base,fini,full,less AUTHOR Michael Savoric, Aug 05 2015 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified January 24 01:05 EST 2020. Contains 331178 sequences. (Running on oeis4.)