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A194352 First of quadruples of consecutive happy numbers. 2
7839, 8739, 11248, 12148, 21148, 44488, 44489, 44939, 49439, 70839, 78039, 80739, 87039, 94439, 101248, 102148, 110248, 112048, 120148, 121048, 201148, 210148, 211048, 222688, 222689, 226288, 226289, 236839, 238639, 258598, 258599, 262288, 262289, 263839 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

Eric Weisstein's World of Mathematics, Happy Number.

EXAMPLE

7839, 7840, 7841, 7842 are the first of four consecutive integers each of which is a happy number, hence a(1) = 7839.

MATHEMATICA

f[n_] := Total[IntegerDigits[n]^2]; t = Select[Range[300000], NestWhile[f, #, UnsameQ, All] == 1 &]; t[[Select[Range[Length[t] - 3],  t[[#]] == t[[# + 1]] - 1 == t[[# + 2]] - 2 == t[[# + 3]] - 3 &]]] (* T. D. Noe, Aug 22 2011 *)

CROSSREFS

Cf. A007770, A035502, A055629, A072494.

Sequence in context: A253752 A252317 A250026 * A234477 A286181 A045277

Adjacent sequences:  A194349 A194350 A194351 * A194353 A194354 A194355

KEYWORD

nonn,base

AUTHOR

Martin Renner, Aug 22 2011

STATUS

approved

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Last modified May 8 21:32 EDT 2021. Contains 343668 sequences. (Running on oeis4.)