A035502 Lower of pair of consecutive happy numbers.

31, 129, 192, 262, 301, 319, 367, 391, 565, 622, 637, 655, 912, 931, 1029, 1092, 1114, 1121, 1151, 1184, 1211, 1221, 1257, 1274, 1299, 1332, 1447, 1474, 1511, 1527, 1574, 1581, 1724, 1744, 1754, 1771, 1784, 1814, 1851, 1874, 1880, 1881, 1902, 1929, 2062

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• easy
• base

References

• R. K. Guy, Unsolved Problems Number Theory, Sect. E34.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000
• Eric Weisstein's World of Mathematics, Happy Number

Crossrefs

Cf. A007770, A035503.

Programs

Mathematica

f[n_] := Total[IntegerDigits[n]^2]; t = Select[Range[5000], NestWhile[f, #, UnsameQ, All] == 1 &]; t[[Select[Range[Length[t] - 1],  t[[#]] == t[[# + 1]] - 1 &]]] (* T. D. Noe, Aug 23 2011 *)

Extensions

More terms from Sascha Kurz, Mar 24 2002