A334557 Numbers m such that m = p^2 + k^2, with p > 0, where p = A007954(m) = the product of digits of m.

1, 13, 41, 61, 125, 212, 281, 613, 1156, 1424, 2225, 3232, 3316, 4113, 11125, 11281, 11525, 12816, 14913, 16317, 16441, 19125, 21284, 21625, 24128, 25216, 27521, 31525, 53125, 56116, 61321, 65161, 71325, 82116, 82217, 83521, 84313, 111812, 113125, 113625, 115336, 115681, 117125, 118372

Offset

1,2

Links

Giovanni Resta, Table of n, a(n) for n = 1..10000

Example

13 is a term as p = 1*3 = 3 and 13 = 3^2 + 2^2.
281 is a term as p = 2*8*1 = 16 and 281 = 16^2 + 5^2.
118372 is a term as p = 1*1*8*3*7*2 = 336 and 118372 = 336^2 + 74^2.

Prog

(PARI) isok(m) = my(p=vecprod(digits(m))); p && issquare(m - p^2); \\ Michel Marcus, May 06 2020

Crossrefs

Cf. A007954, A000404, A078134, A334542, A334558.

Sequence in context: A337146 A122730 A101167 * A146238 A039339 A031373

Adjacent sequences: A334554 A334555 A334556 * A334558 A334559 A334560

Keyword

nonn,base

Author

Scott R. Shannon, May 06 2020

Status

approved