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 A193573 Least happy number with next happy number of distance n. 0
 31, 68, 7, 19, 23, 1, 219, 293, 70, 193, 208, 32, 748, 1233, 1457, 973, 263, 338, 49, 109, 763, 5606, 239, 1487, 8884, 1933, 1636, 139, 1607, 3932, 409, 18280, 17966, 4366, 4960, 16181, 33464, 3564, 18899, 496, 4995, 566 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The next term, a(43), equals 144164. [From Harvey P. Dale, Aug 27 2011] LINKS Weisstein, Eric E.: MathWorld -- Happy Number EXAMPLE a(1) = 31 since next happy number is 32 with distance 1. a(2) = 68 since next happy number is 70 with distance 2. a(3) = 7 since next happy number is 10 with distance 3. MATHEMATICA hapQ[n_]:=Last[NestWhileList[Total[IntegerDigits[#]^2]&, n, !MemberQ[{0, 1, 4, 16, 20, 37, 42, 58, 89, 145}, #]&]]==1; Transpose[With[ {hapnos= Partition[ Select[Range[34000], hapQ], 2, 1]}, Table[First[Select[ hapnos, Last[#]-First[#]==n&]], {n, 42}]]][[1]] (* Harvey P. Dale, Aug 27 2011 *) CROSSREFS Cf. A007770. Sequence in context: A142110 A110831 A212723 * A086042 A086051 A109309 Adjacent sequences:  A193570 A193571 A193572 * A193574 A193575 A193576 KEYWORD nonn,base AUTHOR Martin Renner, Jul 31 2011 STATUS approved

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Last modified June 24 20:13 EDT 2021. Contains 345425 sequences. (Running on oeis4.)