A154716 Products of three consecutive happy primes A035497.

1729, 5681, 13547, 56327, 237553, 789289, 1089019, 1560553, 2530217, 4480109, 7703209, 12131401, 18417101, 24119467, 30355679, 38022301, 46039783, 53272619, 57627329, 62188859, 79075651, 112140029, 169169677, 226833263, 271152373, 300157327, 325898231

Offset: 1

Author

Omar E. Pol, Jan 18 2009

Keywords

• easy
• nonn
• base

Comments

Note that a(1) = 1729 is the Hardy-Ramanujan number (see taxicab numbers in A001235, A011541).

Crossrefs

Cf. A001235, A011541, A035497, A154717, A154728, A154729.

Programs

Mathematica

happyQ[n_, b_] := NestWhile[Total[IntegerDigits[#, b]^2] &, n, UnsameQ, All] == 1; Times @@@ Partition[Select[Prime[Range[150]], happyQ[#, 10] &], 3, 1] (* Amiram Eldar, Jan 17 2025 *)

Extensions

a(5)-a(27) from Nathaniel Johnston, Apr 30 2011